Synthetic process for the manufacture of ecteinascidin compounds

ABSTRACT

This invention relates to compounds of formula II: wherein R 1 , R 2 , Prot SH , and Prot NH  are as defined, to processes for the synthesis of ecteinascidins of formula I from compounds of formula II, and to processes for the synthesis of compounds of formula II.

The present invention relates to synthetic processes, and in particularit relates to synthetic processes for producing ecteinascidin compounds.

BACKGROUND OF THE INVENTION

Ecteinascidins is a group of naturally occurring marine compounds andanalogs thereof, which are well identified and structurallycharacterized, and are disclosed to have antibacterial and cytotoxicproperties. See for example, European Patent 309.477; WO 03/66638; WO03/08423; WO 01/77115; WO 03/014127; R. Sakai et al., 1992, Proc. Natl.Acad. Sci. USA 89, pages 11456-11460; R. Menchaca et al., 2003, J. Org.Chem. 68(23), pages 8859-8866; and I. Manzanares et al., 2001, Curr.Med. Chem. Anti-Cancer Agents, 1, pages 257-276; and references therein.Examples of ecteinascidins are provided by ET-743, ET-729, ET-745,ET-759A, ET-759B, ET-759C, ET-770, ET-815, ET-731, ET-745B, ET-722,ET-736, ET-738, ET-808, ET-752, ET-594, ET-552, ET-637, ET-652, ET-583,ET-597, ET-596, ET-639, ET-641, and derivatives thereof, such asacetylated forms, formylated forms, methylated forms, and oxide forms.

The structural characterizations of such ecteinascidins are not givenagain explicitly herein because from the detailed description providedin such references and citations any person of ordinary skill in thistechnology is capable of obtaining such information directly from thesources cited here and related sources.

At least one of the ecteinascidin compounds, ecteinascidin 743 (ET-743),has been extensively studied, and it will be referred to specificallyherein to illustrate features of this invention. ET-743 is beingemployed as an anticancer medicament, under the internationalnonproprietary name (INN) trabectedin, for the treatment of patientswith advanced and metastatic soft tissue sarcoma (STS), after failure ofanthracyclines and ifosfamide, or who are unsuited to receive suchagents, and for the treatment of relapsed platinum-sensitive ovariancancer in combination with pegylated liposomal doxorubicin.

ET-743 has a complex tris(tetrahydroisoquinoline) structure of formula

It was originally prepared by isolation from extracts of the marinetunicate Ecteinascidia turbinata. The yield was low, and alternativepreparative processes had been sought.

The first synthetic process for producing ecteinascidin compounds wasdescribed in U.S. Pat. No. 5,721,362. This process employed sesamol asstarting material and yielded ET-743 after a long and complicatedsequence of 38 examples each describing one or more steps in thesynthetic sequence.

An improvement in the preparation of one intermediate used in suchprocess was disclosed in U.S. Pat. No. 6,815,544. Even with thisimprovement, the total synthesis was not suitable for manufacturingET-743 at an industrial scale.

A hemisynthetic process for producing ecteinascidin compounds wasdescribed in EP 1.185.536. This process employs cyanosafracin B asstarting material to provide ET-743. Cyanosafracin B is a pentacyclicantibiotic obtained by fermentation from the bacteria Pseudomonasfluorescens.

An improvement in such hemisynthetic process was disclosed in EP1.287.004.

To date four additional synthetic process (2 total and 2 formalsynthesis) have been disclosed in patent applications JP 2003221395, WO2007/045686, and WO 2007/087220 and in J. Org. Chem. 2008, 73, pages9594-9600.

WO 2007/045686 also relates to the synthesis of Ecteinascidins-583 and597 using intermediate compounds of formula:

Total synthesis strategies for the synthesis of the pentacyclic core ofET-743 are overviewed in Figure I.

OBJECT OF THE INVENTION

The need remains for alternative hemisynthetic routes to theecteinascidin compounds and related compounds. Such synthetic routes mayprovide more economic paths to the known antitumour agents as well aspermitting the preparation of new active compounds.

SUMMARY OF THE INVENTION

This invention relates to a process for the synthesis of ecteinascidins.It also relates to intermediates for such process, to processes fortheir manufacture, and to their use in the synthesis of ecteinascidins.

In a first aspect, the invention relates to a process step for themanufacture of an ecteinascidin of formula I:

whereinR₁ and R₄ are independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, C(═O)R^(a), C(═O)OR^(b),C(═O)NR^(c)R^(d), and a protecting group for OH;R₂ is selected from hydrogen, substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, C(═O)R^(a), C(═O)OR^(b), C(═O)NR^(c)R^(d),and a protecting group for amino;R₃ is CN or OH;R₅ and R₆ together to the carbon to which they are attached form agroup:

(a) C(═O);

(b) CH(OR₇) or CH(NR₈R₉) wherein R₇ is selected from hydrogen,substituted or unsubstituted C₁-C₁₂ alkyl, substituted or unsubstitutedC₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂ alkynyl, substitutedor unsubstituted aryl, substituted or unsubstituted heterocyclic group,and a protecting group for OH; and R₈ and R₉ are independently selectedfrom hydrogen, substituted or unsubstituted C₁-C₁₂ alkyl, substituted orunsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl, substituted or unsubstituted aryl, substituted or unsubstitutedheterocyclic group, and a protecting group for amino;

(c) a group of formula:

whereinX₁ and X₂ are independently selected from hydrogen and substituted orunsubstituted C₁-C₁₂ alkyl;R₁₀ is selected from hydrogen, C(═O)R^(a), C(═O)OR^(b),C(═O)NR^(c)R^(d), substituted or unsubstituted C₁-C₁₂ alkyl, substitutedor unsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl and a protecting group for OH;R₁₁ is selected from hydrogen, C(═O)R^(a), C(═O)OR^(b),C(═O)NR^(c)R^(d), substituted or unsubstituted C₁-C₁₂ alkyl, substitutedor unsubstituted C₂-C₁₂ alkenyl, and substituted or unsubstituted C₂-C₁₂alkynyl and a protecting group for amino; or

(d) a group of formula:

whereinY₁ is selected from hydrogen, OR^(b), OC(═O)R^(a), OC(═O)OR^(b),OC(═O)NR^(c)R^(d), SR^(e), SOR^(a), SO₂R^(a), C(═O)R^(a), C(═O)OR^(b),C(═O)NR^(c)R^(d), NO₂, NR^(c)R^(d), N(R^(c))C(═O)R^(a), N(R^(c))—OR^(b),C(R^(a))═NOR^(b), N(R^(c))C(═O)OR^(b), N(R^(c))C(═O)NR^(c)R^(d), CN,halogen, substituted or unsubstituted C₁-C₁₂ alkyl, substituted orunsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl, substituted or unsubstituted aryl, and substituted orunsubstituted heterocyclic group;Y₂ and Y₃ are independently selected from hydrogen and substituted orunsubstituted C₁-C₁₂ alkyl;R₁₂ and R₁₃ are independently selected from hydrogen, C(═O)R^(a),C(═O)OR^(b), C(═O)NR^(c)R^(d), substituted or unsubstituted C₁-C₁₂alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl, and substituted orunsubstituted C₂-C₁₂ alkynyl; andeach R^(a) is independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, substituted orunsubstituted aryl, and substituted or unsubstituted heterocyclic group;each R^(b) is independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, substituted orunsubstituted aryl, substituted or unsubstituted heterocyclic group, anda protecting group for OH;each R^(c) and R^(d) is independently selected from hydrogen,substituted or unsubstituted C₁-C₁₂ alkyl, substituted or unsubstitutedC₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂ alkynyl, substitutedor unsubstituted aryl, substituted or unsubstituted heterocyclic group,and a protecting group for amino;each R^(e) is independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, substituted orunsubstituted aryl, substituted or unsubstituted heterocyclic group, anda protecting group for SH;or a pharmaceutical acceptable salt thereof,wherein the process comprises the step of reducing a quinone of formulaII followed by alkylation of the resulting hydroquinone with a suitableelectrophilic reagent to give a compound of formula IIa in accordancewith Scheme I:

whereinR₁ is a protecting group for OH;R₂ is selected from substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, C(═O)R^(a), C(═O)OR^(b), C(═O)NR^(c)R^(d),and a protecting group for amino;R^(a) is selected from hydrogen, substituted or unsubstituted C₁-C₁₂alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl, andsubstituted or unsubstituted heterocyclic group;R^(b) is independently selected from substituted or unsubstituted C₁-C₁₂alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heterocyclic group, and a protecting groupfor OH;R^(c) and R^(d) are independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, substituted orunsubstituted aryl, substituted or unsubstituted heterocyclic group, anda protecting group for amino;Prot^(NH) is a protecting group for amino; andProt^(SH) is a protecting group for SH.

In another aspect, the present invention provides intermediates offormula II:

whereinR₁ is a protecting group for OH;R₂ is selected from substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, C(═O)R^(a), C(═O)OR^(b), C(═O)NR^(c)R^(d),and a protecting group for amino;R^(a) is selected from hydrogen, substituted or unsubstituted C₁-C₁₂alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl, andsubstituted or unsubstituted heterocyclic group;R^(b) is selected from substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heterocyclic group, and a protecting groupfor OH;R^(c) and R^(d) are independently selected from hydrogen, substituted orunsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl,substituted or unsubstituted C₂-C₁₂ alkynyl, substituted orunsubstituted aryl, substituted or unsubstituted heterocyclic group, anda protecting group for amino;Prot^(NH) is a protecting group for amino; andProt^(SH) is a protecting group for SH.

In one particular aspect, the invention relates to the use ofintermediates of formula II in the manufacture of compounds of formulaI.

In a further aspect, the invention relates to a process for thesynthesis of a compound of formula II comprising the demethylation of amethoxybenzoquinone of formula IIa′ in accordance to Scheme II:

wherein R₁, R₂, Prot^(NH), and Prot^(SH) are as defined in formula II.

In another aspect, the invention relates to an alternative process forthe synthesis of a compound of formula II comprising the deprotectionand oxidation of a protected hydroquinone of formula IIa′ in accordanceto Scheme III:

wherein:R₁ and Prot₁ ^(OH) are protecting groups for OH, with the proviso thatR₁ is selected to be removed selectively in the presence of Prot₁ ^(OH)and vice versa; and

R₂, Prot^(NH), and Prot^(SH) are as defined in formula II.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to processes for the manufacture ofcompounds of general formula I and II as defined above.

In the compounds defined by Markush formulae in this specification, thegroups can be selected in accordance with the following guidance:

Alkyl groups may be branched or unbranched, and preferably have from 1to about 12 carbon atoms. One more preferred class of alkyl groups hasfrom 1 to about 6 carbon atoms. Even more preferred are alkyl groupshaving 1, 2, 3 or 4 carbon atoms. Methyl, ethyl, n-propyl, isopropyl andbutyl, including n-butyl, tert-butyl, sec-butyl and isobutyl areparticularly preferred alkyl groups in the compounds of the presentinvention.

Preferred alkenyl and alkynyl groups in the compounds of the presentinvention may be branched or unbranched, have one or more unsaturatedlinkages and from 2 to about 12 carbon atoms. One more preferred classof alkenyl and alkynyl groups has from 2 to about 6 carbon atoms. Evenmore preferred are alkenyl and alkynyl groups having 2, 3 or 4 carbonatoms.

Suitable aryl groups in the compounds of the present invention includesingle and multiple ring compounds, including multiple ring compoundsthat contain separate and/or fused aryl groups. Typical aryl groupscontain from 1 to 3 separated or fused rings and from 6 to about 18carbon ring atoms. Preferably aryl groups contain from 6 to about 14carbon ring atoms. Specially preferred aryl groups include substitutedor unsubstituted phenyl, substituted or unsubstituted naphthyl,substituted or unsubstituted biphenyl, substituted or unsubstitutedphenanthryl and substituted or unsubstituted anthryl. The most preferredaryl group is substituted or unsubstituted phenyl.

Suitable heterocyclic groups include heteroaromatic and heteroalicyclicgroups containing from 1 to 3 separated or fused rings and from 5 toabout 18 ring atoms. Preferably heteroaromatic and heteroalicyclicgroups contain from 5 to about 10 ring atoms, more preferably 5, 6 or 7ring atoms. Suitable heteroaromatic groups in the compounds of thepresent invention contain one, two or three heteroatoms selected from N,O or S atoms and include, e.g., coumarinyl including 8-coumarinyl,quinolyl including 8-quinolyl, isoquinolyl, pyridyl, pyrazinyl,pyrazolyl, pyrimidinyl, furyl, pyrrolyl, thienyl, thiazolyl,isothiazolyl, triazolyl, tetrazolyl, isoxazolyl, oxazolyl, imidazolyl,indolyl, isoindolyl, indazolyl, indolizinyl, phthalazinyl, pteridinyl,purinyl, oxadiazolyl, thiadiazolyl, furazanyl, pyridazinyl, triazinyl,cinnolinyl, benzimidazolyl, benzofuranyl, benzofurazanyl,benzothiophenyl, benzothiazolyl, benzoxazolyl, quinazolinyl,quinoxalinyl, naphthyridinyl and furopyridyl. Suitable heteroalicyclicgroups in the compounds of the present invention contain one, two orthree heteroatoms selected from N, O or S atoms and include, e.g.,pyrrolidinyl, tetrahydrofuranyl, dihydrofuranyl, tetrahydrothienyl,tetrahydrothiopyranyl, piperidyl, morpholinyl, thiomorpholinyl,thioxanyl, piperazinyl, azetidinyl, oxetanyl, thietanyl, homopiperidyl,oxepanyl, thiepanyl, oxazepinyl, diazepinyl, thiazepinyl,1,2,3,6-tetrahydropyridyl, 2-pyrrolinyl, 3-pyrrolinyl, indolinyl,2H-pyranyl, 4H-pyranyl, dioxanyl, 1,3-dioxolanyl, pyrazolinyl,dithianyl, dithiolanyl, dihydropyranyl, dihydrothienyl, dihydrofuranyl,pyrazolidinyl, imidazolinyl, imidazolidinyl, 3-azabicyclo[3.1.0]hexyl,3-azabicyclo[4.1.0]heptyl, 3H-indolyl, and quinolizinyl.

The groups above mentioned may be substituted at one or more availablepositions by one or more suitable groups such as OR′, ═O, SR′, SOR′,SO₂R′, NO₂, NHR′, NR′R′, ═N—R′, NHCOR′, N(COR′)₂, NHSO₂R′,NR′C(═NR′)NR′R′, CN, halogen, COR′, COOR′, OCOR′, OCONHR′, OCONR′R′,CONHR′, CONR′R′, protected OH, protected amino, protected SH,substituted or unsubstituted C₁-C₁₂ alkyl, substituted or unsubstitutedC₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂ alkynyl, substitutedor unsubstituted aryl, and substituted or unsubstituted heterocyclicgroup, wherein each of the R′ groups is independently selected from thegroup consisting of hydrogen, OH, NO₂, NH₂, SH, CN, halogen, COH,COalkyl, CO₂H, substituted or unsubstituted C₁-C₁₂ alkyl, substituted orunsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl, substituted or unsubstituted aryl, and substituted orunsubstituted heterocyclic group. Where such groups are themselvessubstituted, the substituents may be chosen from the foregoing list.

Suitable halogen substituents in the compounds of the present inventioninclude F, Cl, Br and I.

Suitable electrophilic reagents are compounds that react with a1,2-dihydroxyaryl compound to give a [1,3]-dioxolo fused aryl compound.Examples of suitable electrophilic reagents include, but not are limitedto, LG₁-CH₂-LG₂ and LG₁-CO-LG₂ where LG₁ and LG₂ are leaving groupswhich can be the same or different.

The term “pharmaceutically acceptable salts” refers to anypharmaceutically acceptable salt which, upon administration to thepatient is capable of providing (directly or indirectly) a compound asdescribed herein. However, it will be appreciated thatnon-pharmaceutically acceptable salts also fall within the scope of theinvention since those may be useful in the preparation ofpharmaceutically acceptable salts. The preparation of salts can becarried out by methods known in the art.

For instance, pharmaceutically acceptable salts of compounds providedherein are synthesized from the parent compound, which contains a basicor acidic moiety, by conventional chemical methods. Generally, suchsalts are, for example, prepared by reacting the free acid or base formsof these compounds with a stoichiometric amount of the appropriate baseor acid in water or in an organic solvent or in a mixture of both.Generally, nonaqueous media like ether, ethyl acetate, ethanol,2-propanol or acetonitrile are preferred. Examples of the acid additionsalts include mineral acid addition salts such as, for example,hydrochloride, hydrobromide, hydroiodide, sulfate, nitrate, phosphate,and organic acid addition salts such as, for example, acetate,trifluoroacetate, maleate, fumarate, citrate, oxalate, succinate,tartrate, malate, mandelate, methanesulfonate and p-toluenesulfonate.Examples of the alkali addition salts include inorganic salts such as,for example, sodium, potassium, calcium and ammonium salts, and organicalkali salts such as, for example, ethylenediamine, ethanolamine,N,N-dialkylenethanolamine, triethanolamine and basic aminoacids salts.

Suitable protecting groups are well known for the skilled person in theart. A general review of protecting groups in organic chemistry isprovided by Wuts, P. G. M. and Greene T. W. in Protecting groups inOrganic Synthesis, 4th Ed. Wiley-Interscience, and by Kocienski P. J. inProtecting Groups, 3^(rd) Ed. Georg Thieme Verlag. These referencesprovide sections on protecting groups for OH, amino, and SH groups. Allthese references are incorporated by reference in their entirety.

Within the scope of the present invention an OH protecting group isdefined to be the O-bonded moiety resulting from the protection of theOH group through the formation of a suitable protected OH group.Examples of such protected OH groups include ethers, silyl ethers,esters, sulfonates, sulfenates and sulfinates, carbonates, andcarbamates. In the case of ethers the protecting group for the OH can beselected from methyl, methoxymethyl, methylthiomethyl,(phenyldimethylsilyl)-methoxymethyl, benzyloxymethyl,p-methoxybenzyloxymethyl, [(3,4-dimethoxybenzyl)oxy]methyl,p-nitrobenzyloxymethyl, o-nitrobenzyl-oxymethyl,[(R)-1-(2-nitrophenyl)ethoxy]methyl, (4-methoxy-phenoxy)-methyl,guaiacolmethyl, [(p-phenylphenyl)oxy]methyl, t-butoxy-methyl,4-pentenyloxymethyl, siloxymethyl, 2-methoxyethoxymethyl,2-cyanoethoxymethyl, bis(2-chloroethoxy)methyl,2,2,2-trichloroethoxymethyl, 2-(trimethylsilyl)ethoxymethyl,menthoxymethyl, O-bis(2-acetoxy-ethoxy)methyl, tetrahydropyranyl,fluorous tetrahydropyranyl, 3-bromotetrahydropyranyl,tetrahydrothiopyranyl, 1-methoxycyclohexyl, 4-methoxytetrahydropyranyl,4-methoxytetrahydrothiopyranyl, 4-methoxy-tetrahydrothiopyranylS,S-dioxide, 1-[(2-chloro-4-methyl)-phenyl]-4-methoxypiperidin-4-yl,1-(2-fluorophenyl)-4-methoxypiperidin-4-yl,1-(4-chlorophenyl)-4-methoxypiperidin-4-yl, 1,4-dioxan-2-yl,tetrahydrofuranyl, tetrahydrothiofuranyl,2,3,3a,4,5,6,7,7α-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl,1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, 2-hydroxyethyl, 2-bromoethyl,1-[2-(trimethylsilyl)ethoxy]ethyl, 1-methyl-1-methoxyethyl,1-methyl-1-benzyloxyethyl, 1-methyl-1-benzyloxy-2-fluoroethyl,1-methyl-1-phenoxyethyl, 2,2,2-trichloroethyl,1,1-dianisyl-2,2,2-trichloroethyl,1,1,1,3,3,3-hexafluoro-2-phenylisopropyl, 1-(2-cyanoethoxy)ethyl,2-trimethylsilylethyl, 2-(benzylthio)ethyl, 2-phenylselenyl)ethyl,t-butyl, cyclohexyl, 1-methyl-1′-cyclopropylmethyl, allyl, prenyl,cinnamyl, 2-phenallyl, propargyl, p-chlorophenyl, p-methoxyphenyl,p-nitrophenyl, 2,4-dinitrophenyl,2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenyl, benzyl, p-methoxybenzyl,3,4-dimethoxybenzyl, 2,6-dimethoxybenzyl, o-nitrobenzyl, p-nitrobenzyl,pentadienylnitrobenzyl, pentadienylnitropiperonyl, halobenzyl,2,6-dichlorobenzyl, 2,4-dichlorobenzyl, 2,6-difluorobenzyl,p-cyanobenzyl, fluorous benzyl, 4-fluorousalkoxybenzyl,trimethylsilylxylyl, p-phenylbenzyl, 2-phenyl-2-propyl,p-acylaminobenzyl, p-azidobenzyl, 4-azido-3-chlorobenzyl,2-trifluoromethylbenzyl, 4-trifluoromethylbenzyl,p-(methylsulfinyl)benzyl, p-siletanylbenzyl, 4-acetoxybenzyl,4-(2-trimethylsilyl)ethoxymethoxybenzyl, 2-naphthylmethyl, 2-picolyl,4-picolyl, 3-methyl-2-picolyl N-oxide, 2-quinolinylmethyl,6-methoxy-2-(4-methylphenyl-4-quinolinemethyl, 1-pyrenylmethyl,diphenylmethyl, 4-methoxydiphenylmethyl, 4-phenyl-diphenylmethyl,p,p′-dinitrobenzhydryl, 5-dibenzosuberyl, triphenylmethyl,tris(4-t-butylphenyl)methyl, α-naphthyldiphenylmethyl,p-methoxyphenyl-diphenylmethyl, di(p-methoxyphenyl)phenylmethyl,tri(p-methoxyphenyl)-methyl,4-(4′-bromophenacyloxy)phenyldiphenyl-methyl,4,4′,4″-tris(4,5-dichlorophthalimidophenyl)methyl,4,4′,4″-tris(levulinoyloxyphenyl)methyl,4,4′,4″-tris(benzoyloxyphenyl)methyl,4,4′-dimethoxy-3″-[N-(imidazolyl-methyl)]trityl,4,4′-dimethoxy-3″-[N-(imidazolylethyl)carbamoyl]trityl,bis(4-methoxyphenyl)-1′-pyrenylmethyl,4-(17-tetrabenzo[a,c,g,i]fluorenyl-methyl)-4,4″-dimethoxytrityl,9-anthryl, 9-(9-phenyl)xanthenyl, 9-phenylthioxanthyl,9-(9-phenyl-10-oxo)anthryl, 1,3-benzodithiolan-2-yl, and4,5-bis(ethoxycarbonyl)-[1,3]-dioxolan-2-yl, benzisothiazolylS,S-dioxide. In the case of silyl ethers the protecting group for the OHcan be selected from trimethylsilyl, triethylsilyl, triisopropylsilyl,dimethylisopropylsilyl, diethylisopropylsilyl, dimethylhexylsilyl,2-norbornyldimethylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl,tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl,di-t-butylmethylsilyl, bis(t-butyl)-1-pyrenylmethoxysilyl,tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl,(2-hydroxystyryl)diisopropylsilyl, t-butylmethoxyphenylsilyl,t-butoxydiphenylsilyl,1,1,3,3-tetraisopropyl-3-[2-(triphenylmethoxy)-ethoxy]disiloxane-1-yl,and fluorous silyl. In the case of esters the protecting group for theOH together with the oxygen atom of the unprotected OH to which it isattached form an ester that can be selected from formate,benzoylformate, acetate, chloroacetate, dichloroacetate,trichloroacetate, trichloroacetamidate, trifluoroacetate,methoxyacetate, triphenyl-methoxy-acetate, phenoxyacetate,p-chlorophenoxyacetate, phenylacetate, diphenylacetate,3-phenylpropionate, bisfluorous chain type propanoyl, 4-pentenoate,4-oxopentanoate, 4,4-(ethylenedithio)-pentanoate,5[3-bis(4-methoxyphenyl)hydroxymethylphenoxy]levulinate, pivaloate,1-adamantoate, crotonate, 4-methoxycrotonate, benzoate,p-phenylbenzoate, 2,4,6-trimethylbenzoate, 4-bromobenzoate,2,5-difluorobenzoate, p-nitrobenzoate, picolinate, nicotinate,2-(azidomethyl)benzoate, 4-azido-butyrate, (2-azidomethyl)phenylacetate,2-{[(tritylthio)oxy]methyl}benzoate,2-{[(4-methoxytritylthio)oxy]methyl}-benzoate,2-{[methyl(tritylthio)amino]-methyl}benzoate,2-{{[(4-methoxytrityl)thio]methylamino}-methyl}benzoate,2-(allyloxy)phenylacetate, 2-(prenyloxymethyl)benzoate,6-(levulinyloxy-methyl)-3-methoxy-2-nitrobenzoate,6-(levulinyloxymethyl)-3-methoxy-4-nitrobenzoate, 4-benzyloxybutyrate,4-trialkylsilyloxybutyrate, 4-acetoxy-2,2-dimethylbutyrate,2,2-dimethyl-4-pentenoate, 2-iodobenzoate, 4-nitro-4-methylpentanoate,o-(dibromomethyl)benzoate, 2-formylbenzene-sulfonate,4-(methylthiomethoxy)butyrate, 2-(methylthiomethoxy-methyl)benzoate,2-(chloroacetoxymethyl)benzoate, 2-[(2-chloroacetoxy)-ethyl]benzoate,2-[2-(benzyloxy)ethyl]benzoate, 2-[2-(4-methoxybenzyloxy)ethyl]benzoate,2,6-dichloro-4-methylphenoxyacetate,2,6-dichloro-4-(1,1,3,3-tetramethylbutyl)phenoxyacetate,2,4-bis(1,1-dimethylpropyl)-phenoxyacetate, chlorodiphenylacetate,isobutyrate, monosuccinoate, (E)-2-methyl-2-butenoate,o-(methoxycarbonyl)benzoate, α-naphthoate, nitrate, alkylN,N,N′,N′-tetramethylphosphorodiamidate, and 2-chlorobenzoate. In thecase of sulfonates, sulfenates and sulfinates the protecting group forthe OH together with the oxygen atom of the unprotected OH to which itis attached form a sulfonate, sulfenate or sulfinate that can beselected from sulfate, allylsulfonate, methanesulfonate,benzylsulfonate, tosylate, 2-[(4-nitrophenyl)ethyl]-sulfonate,2-trifluoromethylbenzenesulfonate, 4-monomethoxytrityl-sulfenate, alkyl2,4-dinitrophenylsulfenate,2,2,5,5-tetramethylpyrrolidin-3-one-1-sulfinate, anddimethylphosphinothiolyl. In the case of carbonates the protecting groupfor the OH together with the oxygen atom of the unprotected OH to whichit is attached form a carbonate that can be selected from methylcarbonate, methoxymethyl carbonate, 9-fluorenylmethyl carbonate, ethylcarbonate, bromoethyl carbonate, 2-(methylthiomethoxy)ethyl carbonate,2,2,2-trichloroethyl carbonate, 1,1-dimethyl-2,2,2-trichloroethylcarbonate, 2-(trimethylsilyl)ethyl carbonate,2-[dimethyl(2-naphthylmethyl)silyl]ethyl carbonate,2-(phenylsulfonyl)ethyl carbonate, 2-(triphenylphosphonio)ethylcarbonate, cis-[4-[[(methoxytrityl)sulfenyl]oxy]tetrahydrofuran-3-yl]oxycarbonate, isobutyl carbonate, t-butyl carbonate, vinyl carbonate, allylcarbonate, cinnamyl carbonate, propargyl carbonate, p-chlorophenylcarbonate, p-nitrophenyl carbonate, 4-ethoxy-1-naphthyl carbonate,6-bromo-7-hydroxycoumarin-4-ylmethyl carbonate, benzyl carbonate,o-nitrobenzyl carbonate, p-nitrobenzyl carbonate, p-methoxybenzylcarbonate, 3,4-dimethoxybenzyl carbonate, anthraquinon-2-ylmethylcarbonate, 2-dansylethyl carbonate, 2-(4-nitrophenyl)ethyl carbonate,2-(2,4-dinitrophenyl)ethyl carbonate, 2-(2-nitrophenyl)propyl carbonate,alkyl 2-(3,4-methylenedioxy-6-nitrophenyl)propyl carbonate,2-cyano-1-phenylethyl carbonate, 2-(2-pyridyl)amino-1-phenylethylcarbonate, 2-[N-methyl-N-(2-pyridyl)]amino-1-phenylethyl carbonate,phenacyl carbonate, 3′,5′-dimethoxybenzoin carbonate, methyldithiocarbonate, and S-benzyl thiocarbonate. And in the case ofcarbamates the protecting group for the OH together with the oxygen atomof the unprotected OH to which it is attached form a carbamate that canbe selected from dimethylthiocarbamate, N-phenylcarbamate,N-methyl-N-(o-nitrophenyl)-carbamate.

Within the scope of the present invention an amino protecting group isdefined to be the N-bonded moiety resulting from the protection of theamino group through the formation of a suitable protected amino group.Examples of protected amino groups include carbamates, ureas, amides,heterocyclic systems, N-alkyl amines, N-alkenyl amines, N-alkynylamines, N-aryl amines, imines, enamines, N-metal derivatives, N—Nderivatives, N—P derivatives, N—Si derivatives, and N—S derivatives. Inthe case of carbamates the protecting group for the amino group togetherwith the amino group to which it is attached form a carbamate that canbe selected from methylcarbamate, ethylcarbamate,9-fluorenylmethyl-carbamate, 2,6-di-t-butyl-9-fluorenylmethylcarbamate,2,7-bis(trimethylsilyl)fluorenylmethylcarbamate,9-(2-sulfo)fluorenylmethyl carbamate,9-(2,7-dibromo)fluorenylmethylcarbamate,17-tetrabenzo[a,c,g,i]fluorenylmethylcarbamate,2-chloro-3-indenylmethylcarbamate, benz[f]inden-3-ylmethylcarbamate,1,1-dioxobenzo[b]-thiophene-2-ylmethylcarbamate,2-methylsulfonyl-3-phenyl-1-prop-2-enyloxycarbamate,2,7-di-t-butyl-[9,(10,10-dioxo-10,10,10,10-tetraydrothioxanthyl)]methylcarbamate,2,2,2-trichloroethylcarbamate, 2-trimethylsilylethylcarbamate,(2-phenyl-2-trimethylsilyl)ethylcarbamate, 2-phenylethylcarbamate,2-chloroethylcarbamate, 1,1-dimethyl-2-haloethylcarbamate,1,1-dimethyl-2,2-dibromoethylcarbamate,1,1-dimethyl-2,2,2-trichloroethylcarbamate,2-(2′-pyridyl)ethylcarbamate, 2-(4′-pyridyl)ethylcarbamate,2,2-bis(4′-nitrophenyl)ethylcarbamate,2-[(2-nitrophenyl)dithio]-1-phenylethylcarbamate,2-(N,N-dicyclohexylcarboxamido)ethylcarbamate, t-butylcarbamate,C₈F₁₉CH₂CH₂C(CH₃)₂-carbamate, 1-adamantylcarbamate, 2-adamantylcarbamate, 1-(1-adamantyl)-1-methylethylcarbamate,1-methyl-1-(4-byphenylyl)ethylcarbamate,1-(3,5-di-t-butylphenyl)-1-methyl-ethylcarbamate,triisoropyliloxylcarbamate, vinylcarbamate, allylcarbamate,prenylcarbamate, 1-isopropylallylcarbamate, cinnamylcarbamate,4-nitrocinnamylcarbamate, 3-(3′-pyridyl)prop-2-enylcarbamate,hexadienyloxycarbamate, propargyloxycarbamate,but-2-ynylbisoxycarbamate, 8-quinolyl-arbamate,N-hydroxypiperidinyl-carbamate, alkyldithiocarbamate, benzylcarbamate,3,5-di-t-butylbenzylcarbamate, p-methoxybenzylcarbamate,p-nitrobenzylcarbamate, p-bromobenzylcarbamate,p-chlorobenzyl-carbamate, 2,4-dichlorobenzylcarbamate,4-methylsulfinylbenzyl-carbamate, 4-trifluoromethylbenzylcarbamate,C₈F₁₇CH₂CH₂-carbamate, (C₈F₁₇CH₂CH₂)₃Si-carbamate,2-naphthylmethylcarbamate, 9-anthryl-methylcarbamate,diphenylmethylcarbamate, 4-phenylacetoxybenzyl-carbamate,4-azidobenzylcarbamate, 4-azidomethoxybenzylcarbamate,m-chloro-p-acyloxybenzylcarbamate, p-(dihydroxyboryl)benzylcarbamate,5-benzisoxazolylmethylcarbamate,2-(trifluoromethyl)-6-chromonylmethyl-carbamate,2-methylthioethylcarbamate, 2-methylsulfonylethylcarbamate,2-(p-toluenesulfonyl)-ethylcarbamate,2-(4-nitrophenylsulfonyl)ethoxy-carbamate,2-(2,4-dinitrophenylsulfonyl)ethoxycarbamate,2-(4-trifluoromethylphenylsulfonyl)ethoxycarbamate,[2-(1,3-dithianyl)]methyl-carbamate, 2-phosphonioethylcarbamate,2-[phenyl(methyl)sulfonio]ethyl-carbamate,1-methyl-1-(triphenylphosphonio)ethylcarbamate,1,1-dimethyl-2-cyanoethylcarbamate, 2-dansylethylcarbamate,2-(4-nitrophenyl)ethylcarbamate, 4-methylthiophenylcarbamate,2,4-dimethylthiophenylcarbamate, m-nitrophenylcarbamate,3,5-dimethoxy-benzylcarbamate,1-methyl-1-(3,5-dimethoxyphenyl)ethylcarbamate,α-methylnitro-piperonylcarbamate, o-nitrobenzylcarbamate,3,4-dimethoxy-6-nitrobenzylcarbamate,phenyl(o-nitrophenyl)methylcarbamate, 2-nitrophenylethylcarbamate,6-nitroveratrylcarbamate, 4-methoxyphenacyl-carbamate,3′,5′-dimethoxybenzoincarbamate, 9-xanthenylmethyl-carbamate,N-methyl-N-(o-nitrophenyl)carbamate, N-(2-acetoxyethyl)-aminecarbamate,t-amylcarbamate, 1-methylcyclobutylcarbamate,1-methylcyclohexylcarbamate, 1-methyl-1-cyclopropylmethylcarbamate,cyclobutylcarbamate, cyclopentylcarbamate, cyclohexylcarbamate,isobutylcarbamate, isobornylcarbamate, cyclopropylmethylcarbamate,p-decyloxybenzylcarbamate, diisopropylmethylcarbamate,2,2-dimethoxy-carbonylyinylcarbamate,o-(N,N-dimethylcarboxamido)benzylcarbamate,1,1-dimethyl-3-(N,N-dimethylcarboxamido)propylcarbamate,butynyl-carbamate, 1,1-dimethylpropynylcarbamate, 2-iodoethylcarbamate,1-methyl-1-(4′-pyridyl)ethylcarbamate,1-methyl-1-(p-phenylazophenyl)ethyl-carbamate,p-(p′-methoxyphenylazo)benzylcarbamate, p-(phenylazo)benzyl-carbamate,2,4,6-trimethylbenzylcarbamate, isonicotinylcarbamate,4-(trimethyl-ammonium)benzylcarbamate, p-cyanobenzylcarbamate,di(2-pyridyl)methylcarbamate, 2-furanylmethylcarbamate, phenylcarbamate,2,4,6-tri-t-butylphenylcarbamate, 1-methyl-1-phenylethylcarbamate, andS-benzyl thiocarbamate. In the case of ureas the protecting groups forthe amino group can be selected from phenothiazinyl-(10)-carbonyl,N′-p-toluenesulfonylaminocarbonyl, N′-phenylaminothio-carbonyl,4-hydroxyphenylaminocarbonyl, 3-hydroxytryptaminocarbonyl, andN′-phenyl-aminothiocarbonyl. In the case of amides the protecting groupfor the amino group together with the amino group to which it isattached form an amide that can be selected from formamide, acetamide,chloroacetamide, trichloroacetamide, trifluoroacetamide,phenyl-acetamide, 3-phenylpropanamide, pent-4-enamide, picolinamide,3-pyridyl-carboxamide, N-benzoylphenylalanyl, benzamide,p-phenylbenzamide, o-nitrophenylacetamide,2,2-dimethyl-2-(o-nitrophenyl)acetamide, o-nitrophenoxyacetamide,3-(o-nitrophenyl)-propanamide, 2-methyl-2-(o-nitrophenoxy)propanamide,3-methyl-3-nitrobutanamide, o-nitrocinnamide, o-nitrobenzamide,3-(4-t-butyl-2,6-dinitrophenyl)-2,2-dimethylpropanamide,o-benzoyloxymethyl)-benzamide, 2-(acetoxymethyl)-benzamide,2-[(t-butyldiphenylsiloxy)-methyl]benzamide,3-(3′,6′-dioxo-2′,4′,5′-trimethylcyclohexa-1′,4′-diene)-3,3-dimethylpropionamide,o-hydroxy-trans-cinnamide, 2-methyl-2-(O-phenylazophenoxy)propanamide,4-chlorobutanamide, acetoacetamide, 3-(p-hydroxyphenyl)propanamide,(N-dithiobenzyloxycarbonylamino)-acetamide, and N-acetylmethionineamide. In the case of heterocyclic systems the protecting group for theamino group together with the amino group to which it is attached form aheterocyclic system that can be selected from4,5-diphenyl-3-oxazolin-2-one, N-phthalimide, N-dichlorophthalimide,N-tetrachlorophthalimide, N-4-nitrophthalimide, N-thiodiglycoloyl,N-dithiasuccinimide, N-2,3-diphenylmaleimide, N-2,3-dimethylmaleimide,N-2,5-dimethylpyrrole, N-2,5-bis(triisopropylsiloxy)pyrrole,N-1,1,4,4-tetramethyldisilylazacyclo-pentane adduct,N-1,1,3,3-tetramethyl-1,3-disilaisoindoline, N-diphenylsilyldiethylene,N-5-substituted-1,3-dimethyl-1,3,5-triazacyclohexan-2-one,N-5-substituted-1,3-benzyl-1,3,5-triazacyclohexan-2-one, 1-substituted3,5-dinitro-4-pyridone, and 1,3,5-dioxazine. In the case of N-alkyl,N-alkenyl, N-alkynyl or N-aryl amines the protecting group for the aminogroup can be selected from N-methyl, N-t-butyl, N-allyl, N-prenyl,N-cinnamyl, N-phenylallyl, N-propargyl, N-methoxymethyl,N-[2-(trimethylsilyl)ethoxy]methyl, N-3-acetoxypropyl, N-cyanomethyl,N-2-azanorbornenes, N-benzyl, N-4-methoxybenzyl, N-2,4-dimethoxybenzyl,N-2-hydroxybenzyl, N-ferrocenylmethyl, N-2,4-dinitrophenyl,o-methoxyphenyl, p-methoxyphenyl, N-9-phenylfluorenyl, N-fluorenyl,N-2-picolylamine N′-Oxide, N-7-methoxycoumar-4-ylmethyl,N-diphenylmethyl, N-bis(4-methoxyphenyl)methyl, N-5-dibenzosuberyl,N-triphenylmethyl, N-(4-methylphenyl)diphenylmethyl, andN-(4-methoxyphenyl)diphenylmethyl. In the case of imines the protectinggroup for the amino group can be selected fromN-1,1-dimethylthiomethylene, N-benzylidene, N-p-methoxybenzylidene,N-diphenylmethylene, N-[2-pyridyl)mesityl]-methylene,N—(N′,N′-dimethylaminomethylene), N—(N′,N′-dibenzylaminomethylene),N—(N′-t-butylaminomethylene), N,N′-isopropylidene, N-p-nitrobenzylidene,N-salicylidene, N-5-chlorosalicylidene,N-(5-chloro-2-hydroxyphenyl)phenylmethylene, N-cyclohexylidene, andN-t-butylidene. In the case of enamines the protecting group for theamino group can be selected from N-(5,5-dimethyl-3-oxo-1-cyclohexenyl),N-2,7-dichloro-9-fluorenylmethylene,N-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl,N-(1,3-dimethyl-2,4,6-(1H,3H,5H)-trioxopyrimidine-5-ylidene)methyl,N-4,4,4-trifluoro-3-oxo-1-butenyl, andN-(1-isopropyl-4-nitro-2-oxo-3-pyrrolin-3-yl). In the case of N-metalderivatives the protecting group for the amino group can be selectedfrom N-borane, N-diphenylborinic acid, N-diethylborinic acid,N-9-borabicyclononane, N-difluoroborinic acid, and3,5-bis(trifluoromethyl)phenylboronic acid; and also includingN-[phenyl(pentacarbonylchromium)]carbenzyl,N-[phenyl(pentacarbonyltungsten)]carbenzyl,N-[methyl(pentacarbonylchromium)]carbenzyl,N-[methyl(pentacarbonyltungsten)]-carbenzyl, N-copper chelate, N-zincchelate, and a 18-crown-6-derivative. In the case of N—N derivatives theprotecting group for the amino group can be selected from N-nitro,N-nitroso, N-oxide, azide, triazene, andN-trimethylsilylmethyl-N-benzylhydrazine. In the case of N—P derivativesthe protecting group for the amino group together with the amino groupto which it is attached form a N—P derivative that can be selected fromdiphenylphosphinamide, dimethylthiophosphinamide,diphenylthiophosphinamide, dialkyl phosphoramidate, dibenzylphosphoramidate, diphenyl phosphoramidate, andiminotriphenylphosphorane. In the case of N—Si derivatives theprotecting group for the NH₂ can be selected from t-butyldiphenylsilyland triphenylsilyl. In the case of N—S derivatives the protecting groupfor the amino group together with the amino group to which it isattached form a N—S derivative that can be selected from N-sulfenyl orN-sulfonyl derivatives. The N-sulfenyl derivatives can be selected frombenzenesulfenamide, 2-nitrobenzenesulfenamide,2,4-dinitrobenzenesulfenamide, pentachloro-benzenesulfenamide,2-nitro-4-methoxybenzenesulfenamide, triphenyl-methylsulfenamide,1-(2,2,2)-trifluoro-1,1-diphenyl)ethylsulfenamide, andN-3-nitro-2-pyridinesulfenamide. The N-sulfonyl derivatives can beselected from methanesulfonamide, trifluoromethanesulfonamide,t-butylsulfonamide, benzylsulfonamide,2-(trimethylsilyl)ethanesulfonamide, p-toluene-sulfonamide,benzenesulfonamide, o-anisylsulfonamide, 2-nitrobenzenesulfonamide,4-nitrobenzenesulfonamide, 2,4-dinitrobenzenesulfonamide,2-naphthalenesulfonamide,4-(4′,8′-dimethoxynaphthylmethyl)benzenesulfonamide,2-(4-methylphenyl)-6-methoxy-4-methylsulfonamide,9-anthracenesulfonamide, pyridine-2-sulfonamide,benzothiazole-2-sulfonamide, phenacylsulfonamide,2,3,6-trimethyl-4-methoxybenzenesulfonamide,2,4,6-trimethoxybenzene-sulfonamide,2,6-dimethyl-4-methoxybenzenesulfonamide,pentamethyl-benzenesulfonamide,2,3,5,6-tetramethyl-4-methoxybenzenesulfonamide,4-methoxybenzenesulfonamide, 2,4,6-trimethylbenzenesulfonamide,2,6-dimethoxy-4-methylbenzenesulfonamide,3-methoxy-4-t-butylbenzenesulfonamide, and2,2,5,7,8-pentamethylchroman-6-sulfonamide.

Within the scope of the present invention an SH protecting group isdefined to be the S-bonded moiety resulting from the protection of theSH group through the formation of a suitable protected SH group.Examples of such protected SH groups include thioethers, disulfides,silyl thioethers, thioesters, thiocarbonates, and thiocarbamates. In thecase of thioethers the protecting group for the SH can be selected fromS-alkyl, S-benzyl, S-p-methoxybenzyl, S-o-hydroxybenzyl,S-p-hydroxybenzyl, S-o-acetoxybenzyl, S-p-acetoxybenzyl,S-p-nitrobenzyl, S-o-nitrobenzyl, S-2,4,6-trimethylbenzyl,S-2,4,6,-trimethoxybenzyl, S-4-picolyl, S-2-picolyl-N-oxide,S-2-quinolinylmethyl, S-9-anthrylmethyl, S-9-fluorenylmethyl,S-xanthenyl, S-ferrocenylmethyl, S-diphenylmethyl,S-bis(4-methoxyphenyl)methyl, S-5-dibenzosuberyl, S-triphenylmethyl,4-methoxytrityl, S-diphenyl-4-pyridylmethyl, S-phenyl,S-2,4-dinitrophenyl, S-2-quinolyl, S-t-butyl, S-1-adamantyl,S-methoxymethyl monothioacetal, S-isobutoxymethyl monothioacetal,S-benzyloxymethyl, S-1-ethoxyethyl, S-2-tetrahydropyranylmonothioacetal, S-benzylthiomethyl dithioacetal, S-phenylthiomethyldithioacetal, thiazolidine derivative, S-acetamidomethyl aminothioacetal(Acm), S-trimethylacetamidomethyl aminothioacetal, S-benzamidomethylaminothioacetal, S-allyloxycarbonylaminomethyl,S—N-[2,3,5,6-tetrafluoro-4-(N′-piperidino)-phenyl-N-allyloxycarbonylamino-methyl,S-phthalimidomethyl, S-phenylacetamidomethyl, S-(2-nitro-1-phenyl)ethyl,S-2-(2,4-dinitrophenyl)ethyl, S-2-(4′-pyridyl)ethyl, S-2-cyanoethyl,S-2-(trimethylsilyl)ethyl, S-2,2-bis(carboethoxy)ethyl,S-(1-m-nitrophenyl-2-benzoyl)ethyl, S-2-phenylsulfonylethyl,S-1-(4-methylphenylsulfonyl)-2-methylprop-2-yl, and S-p-hydroxyphenacyl.In the case of disulfides the protecting group for the SH can beselected from S—S-Et, S—S-tBu[S-(tert-butylsulfanyl)cysteine,S—S-tbutyl) and S-Npys (S-3-nitro-2-pyridinesulfenyl). In the case ofsilyl thioethers the protecting group for the SH can be selected fromthe list of groups that was listed above for the protection of OH withsilyl ethers. In the case of thioesters the protecting group for the SHcan be selected from S-acetyl, S-benzoyl, S-2-methoxyisobutyryl,S-trifluoroacetyl, and the protecting group for the SH together with theSH group to which it is attached form a thioester that can be selectedfromS—N-[[p-biphenylyl)-isopropoxy]carbonyl]-N-methyl-γ-aminothiobutyrate,and S—N-(t-butoxycarbonyl)-N-methyl-γ-aminothiobutyrate. In the case ofthiocarbonate protecting group for the SH can be selected fromS-2,2,2-trichloroethoxycarbonyl, S-t-butoxycarbonyl,S-benzyloxycarbonyl, S-p-methoxybenzyloxycarbonyl, andS-fluorenylmethylcarbonyl. In the case of thiocarbamate the protectinggroup for the SH together with the SH group to which it is attached forma thiocarbamate that can be selected from S—(N-ethylcarbamate) andS—(N-Methoxymethylcarbamate).

The mention of these groups should not be interpreted as a limitation ofthe scope of the invention, since they have been mentioned as a mereillustration of protecting groups for OH, amino and SH groups, butfurther groups having said function may be known by the skill person inthe art, and they are to be understood to be also encompassed by thepresent invention.

Suitable coupling agents are well known for the skilled person in theart. Examples of coupling agents are N,N′-dicyclohexylcarbodiimide(DCC), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and itssalts, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide (EDCmethiodide), N,N′-diisopropylcarbodiimide,1-tert-butyl-3-ethylcarbodiimide,N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate(CMC), N,N′-di-tert-butylcarbodiimide, 1,3-Di-p-tolylcarbodiimide,1,1′-carbonyldiimidazole (CDI), 1,1′-carbonyl-di-(1,2,4-triazole) (CDT),oxalic acid diimidazolide, 2-chloro-1,3-dimethylimidazolidinium chloride(DMC), 2-chloro-1,3-dimethylimidazolidinium tetrafluoroborate (CIB),2-chloro-1,3-dimethylimidazolidinium hexafluorophosphate (CIP),2-fluoro-1,3-dimethylimidazolidinium hexafluorophosphate (DFIH),(benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate(BOP), (benzotriazol-1-yloxy)tripyrrolidinophosphoniumhexafluorophosphate, 7-azabenzotriazol-1-yloxy)tripyrrolidinophosphoniumhexafluorophosphate (PyAOP), bromotris(dimethylamino)phosphoniumhexafluorophosphate (BRoP), chlorotripyrrolidinophosphoniumhexafluorophosphate (PyClOP), bromotripyrrolidinophosphoniumhexafluorophosphate,3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT),O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate(HBTU), O-(benzotriazol-1-yl)-N,N′,N,′-tetramethyluroniumtetrafluoroborate (TBTU),O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HATU),0-(benzotriazol-1-yl)-N,N,N′,N′-bis(tetramethylene)uroniumhexafluorophosphate (HBPyU),O-benzotriazol-1-yl-N,N,N′,N′-bis(pentamethylene)uroniumhexafluorophosphate (HBPipU),(benzotriazol-1-yloxy)dipiperidinocarbenium tetrafluoroborate (TBPipU),O-(6-chlorobenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HCTU),O-(6-chlorobenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium (TCTU),O-(3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl)-N,N,N′,N′-tetramethyluroniumtetrafluoroborate (TDBTU),O-(2-oxo-1(2H)pyridyl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate(TPTU),O-[(ethoxycarbonyl)cyanomethylenamino]-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HOTU),O-[(ethoxycarbonyl)cyanomethylenamino]-N,N,N′,N′-tetramethyluroniumtetrafluoroborate (TOTU),N,N,N′,N′-tetramethyl-O—(N-succinimidyl)uronium hexafluorophosphate(HSTU), N,N,N′,N′-tetramethyl-O—(N-succinimidyl)uroniumtetrafluoroborate (TSTU), dipyrrolidino (N-succinimidyloxy)carbenium(HSPyU), propylphosphonic anhydride (T3P) andS-(1-oxido-2-pyridyl)-N,N,N′,N′-tetramethylthiouronium tetrafluoroborate(TOTT).

In the present description and definitions, when there are severalgroups R^(a), R^(b), R^(c), R^(d) or R^(e) present in the compounds ofthe invention, and unless it is stated explicitly so, it should beunderstood that they can be each independently different within thegiven definition, i.e. R^(a) does not represent necessarily the samegroup simultaneously in a given compound of the invention.

The compounds of formula I can be obtained synthetically fromintermediates of formula II following the sequence of key reactionsindicated in Scheme IV:

whereinR₁, R₂, Prot^(NH), and Prot^(SH) in the compounds of formula II, IIa,IIIb, Ia, and Ib are as defined above in intermediates of formula II;R₂, R₃, R₇, R₈, R₉, R₁₀, R₁₁, R₁₂, R₁₃, X₁, X₂, Y₁, Y₂, and Y₃ in thecompounds of formula Ic, Id, Ie, If, and Ig are as defined above inecteinascidins of formula I;LG is a leaving group; andR₇, R₈, R₉, R₁₀, R₁₁, R₁₂, and R₁₃ in the compounds of formula R₇-LG,R₈-LG, R₉-LG, R₁₀-LG, R₁₁-LG, R₁₂-LG, and R₁₃-LG, respectively, are asdefined above in ecteinascidins of formula I with the proviso that theyare not hydrogen.

Examples of leaving groups include, but are not limited to, iodine,bromine, chlorine, tosylate, mesylate, nosylate, betylate, alkylfluorosulfonate, triflate, and nonaflate.

In general, the conversion of the intermediates of formula II to anecteinascidin compound of formula I may involve one or more of thefollowing key transformations as needed:

(a) Reduction of the quinone group in the compound of formula IIfollowed by alkylation of the resulting hydroquinone with a suitableelectrophilic reagent to give a compound of formula IIa.

(b) Oxidation of the compound of formula IIa to give a compound offormula IIb.

(c) Formation of the bridged ring system to provide a compound offormula Ia.

(d) Deprotection of the phenol and amino groups to give a compound offormula Ib.

(e) Conversion of the compound of formula Ib to give a compound offormula Ic.

(f) Oxidation of the α-aminolactone of formula Ib to the correspondingα-ketolactone of formula Id by transamination.

(g) Stereospecifically forming of aspirotetrahydro-1H-pyrido[3,4-b]indole of formula Ie or aspirotetrahydroisoquinoline of formula If by a Pictet-Spengler reactionfrom the α-ketolactone of formula Id.

(h) Reduction of the α-ketolactone of formula Id to the correspondingα-hydroxylactone of formula Ig.

(i) Replacing the cyano in R₃ by a hydroxy group.

Step (a) is typically effected by reduction of the quinone system into ahydroquinone using a transition-metal catalysed hydrogenation or areducting reagent such as Na₂S₂O₄, followed by trapping with a suitableelectrophile reagent, such as CH₂Br₂, BrCH₂Cl or a similar divalentreagent, directly yielding the methylenedioxy ring system; or with adivalent reagent, such as thiocarbonyldiimidazole, which yields asubstituted methylenedioxy ring system that can be converted to thedesired ring.Step (b) is typically effected by reaction with a suitable oxidant, forexample with hydrogen peroxide, an organic peroxide, a perbenzoic acid,a periodate, lead tetraacetate, lead oxide, selenium dioxide,hypervalent iodine oxidants such as 2-iodoxybenzoic acid (IBX), or withan organic seleninic anhydride such as (PhSeO)₂O. More preferredoxidants are organic seleninic anhydrides and hypervalent iodineoxidants. Organic seleninic anhydrides are even more preferred. The mostpreferred oxidant is (PhSeO)₂O.Step (c) is typically effected by forming an exendo quinone methide atthe 4-position of ring B, allowing the methide to react with the sulphuratom of the cysteine residue and capturing the resulting phenoxide withan acetylating reagent such as acetic anhydride, a mixed acetylanhydride, or acetyl chloride to give a compound of formula Ia. Suitablethe methide is formed by reaction of the compound of formula IIb withthe in situ-generated Swern reagent, followed by treatment with a base.Suitable the cyclization is carried out by removing the protecting groupfor SH under conditions that allow the formation of a thiolate ion,followed by nucleophile addition of sulphur to the quinone methide togenerate the 10-membered lactone bridge, and the resulting phenoxide iscaptured to give the acetate of formula Ia.Step (d) is preferably effected by deprotection of the phenol and aminogroups in a single step rather than as two separate steps. Morepreferably, the one-pot deprotection is carried out under acidicconditions.Step (e) is carried out when R₈ and/or R₉ are not hydrogen and istypically effected by reaction with a compound of formula R₈LG or R₉LGand, when both R₈ and R₉ are not hydrogen, followed by a second reactionwith a compound of formula R₉LG or R₈LG, respectively.Step (f) is typically effected by an oxidative conversion of the aminogroup into the corresponding oxo group by reaction with a suitablecarbonyl reagent such as a hindered 1,2-benzoquinone or a pyridine- orpyridinium carboxaldehyde. More preferred carbonyl reagents are themethiodide of pyridine-4-carboxaldehyde and the methylbencene-sulfonateof pyridine-4-carboxaldehyde.Step (g) is typically effected by Pictet-Spengler reaction with aβ-arylethylamine of formula:

wherein Y₁, Y₂, Y₃, X₁, and X₂ are as defined above in ecteinascidins offormula I.Step (h) is typically effected by reaction with a suitable reductingreagent. Examples of suitable reducting reagents are alkoxy aluminumhydrides and boron hydrides, for example borohydrides andcyanoborohydrides. More preferred reducting reagents are borohydridesand cyanoborohydrides. The most preferred reducting reagent is NaCNBH₃in the presence of acetic acid.Step (i) is typically carried out by reaction with anitrile-coordinating transition metal salt. More preferred salts aresalts of Ag(I) or Cu(I). The most preferred salts are AgNO₃ and CuCl.

Further transformations may be required to obtain certain compounds offormula I and for this purpose the procedures described in WO 01/87895,WO 03/014127, WO 03/66638, WO 03/08423 and WO 01/77115, which areincorporated herein in full by reference, can be followed.

Preferred processes for the synthesis of compounds of formula Ie arethose that provide compounds of formula Ie′:

where R₂, R₃, R₁₂, R₁₃, Y₁, Y₂, and Y₃ are as defined above inecteinascidins of formula I.

Particularly preferred processes for the synthesis of compounds offormula I are those that provide compounds of formula Ic, Id, Ie, Ie′,If, or Ig wherein R₂ is methyl, R₃ is hydroxy, X₁, X₂, Y₂, Y₃, R₇, R₈,R₉, R₁₀, R₁₁, R₁₂, and R₁₃ are hydrogen, and Y₁ is selected fromhydrogen and methoxy.

Particularly preferred processes for the synthesis of compounds offormula I are those that employ ether protected OH groups. Morepreferably ether protected OH groups are methoxyethoxymethyl ether andmethoxymethyl ether. The most preferred ether protected OH group ismethoxyethoxymethyl ether.

Particularly preferred processes for the synthesis of compounds offormula I are those that employ carbamate protected amino groups. Morepreferably carbamate protected amino groups are selected fromallylcarbamate, 2,2,2-trichloroethylcarbamate, benzylcarbamate,9-fluorenylmethyl-carbamate, and t-butylcarbamate. The most preferredcarbamate protected amino group is t-butylcarbamate.

Particularly preferred processes are those that employ thioetherprotected SH groups. More preferably thioether protected SH groups aresubstituted or unsubstituted S-9-fluorenylmethyl thioethers. The mostpreferred thioether protected SH group is S-9-fluorenylmethyl (Fm)thioether.

More preferred processes for the synthesis of compounds of formula I arethose that give compounds of formula:

In addition, with this invention we provide novel intermediate compoundsof formula II:

wherein R₁, R₂, Prot^(SH) and Prot^(NH) are as defined above in theprevious disclosure of intermediates of formula II.

In compounds of formula II, particularly preferred R₁ is a protectinggroup for OH that together with the O atom to which it is attached forman ether. More preferably R₁ is methoxyethoxymethyl or methoxymethyl.The most preferred R₁ is methoxyethoxymethyl.

Particularly preferred R₂ is a substituted or unsubstituted C₁-C₆ alkyl,a substituted or unsubstituted C₂-C₆ alkenyl or C(═O)OR^(b), where R^(b)is selected from substituted or unsubstituted C₁-C₆ alkyl andsubstituted or unsubstituted C₂-C₆ alkenyl. Particularly preferred R₂ isan unsubstituted C₁-C₆ alkyl or an unsubstituted C₂-C₆ alkenyl. Morepreferably R₂ is methyl or allyl. The most preferred R₂ is methyl.

Particularly preferred Prot^(NH) is a protecting group for amino thattogether with the N atom to which is attached form a carbamate. Morepreferably Prot^(NH) is selected from allyloxycarbonyl,2,2,2-trichloroethyloxycarbonyl, benzyloxycarbonyl,9-fluorenylmethyloxycarbonyl, and t-butyloxycarbonyl. The most preferredProt^(NH) is t-butyloxycarbonyl.

Particularly preferred Prot^(SH) is a protecting group for SH thattogether with the S group to which is attached form a thioether. Morepreferably Prot^(SH) is a substituted or unsubstitutedS-9-fluorenylmethyl. The most preferred Prot^(SH) is S-9-fluorenylmethyl(Fm).

Suitable starting materials for the synthesis of the intermediates offormula II include compounds related to the naturalbis(tetrahydroisoquinoline) alkaloids. Such starting materials may beprepared either from the different classes of saframycin and safracinantibiotics available from different culture broths as detailed in WO00/69862 or by other synthetic or biochemical processes such as thosedisclosed in U.S. Pat. No. 5,721,362, U.S. Pat. No. 6,815,544, JP2003221395, WO 2007/045686, WO 2007/087220 and J. Org. Chem. 2008, 73,9594-9600, which are all incorporated herein in full by reference.

In one embodiment, compounds of formula II are obtained fromcyanosafracin B following the sequence of reactions indicated in SchemeV:

wherein:Prot^(OH) is a protecting group for OH;Ar is a substituted or unsubstituted aryl group;Prot^(NH) is a protecting group for amino;Prot^(SH) is a protecting group for SH; andR₁ and R₂ are as defined above in formula II.

Accordingly, in this embodiment, the process for the synthesis of acompound of formula II comprises the step of demethylating amethoxyquinone of formula IIa′:

wherein R₁, R₂, Prot^(NH) and Prot^(SH) are as defined above in theprevious disclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IIa′ by protecting a phenol of formula IIb′:

wherein R₁, R₂, Prot^(NH) and Prot^(SH) are as defined above in theprevious disclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IIb′ by oxidation of a hydroquinone of formula IIc′:

wherein R₂, Prot^(NH) and Prot^(SH) are as defined above in the previousdisclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing acompound of formula IIc′ by deprotection of a compound of formula IId′:

wherein R₂, Prot^(OH), Prot^(NH) and Prot^(SH) are as defined above inthe previous disclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IId′ by coupling the primary hydroxyl group in acompound of formula IIe′ with a protected cysteine derivative:

wherein R₂, Prot^(OH), Prot^(NH) and Prot^(SH) are as defined above inthe previous disclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IIe′ by converting a primary amine of formula IIf′to a primary alcohol with a suitable oxidizing reagent and, optionally,when R₂ in the compound of formula IIe′ is not methyl, followed byprotecting the primary alcohol with a silyl protecting group for OH,demethylating the NMe group, reacting the resulting secundary amine witha compound of formula R₂-LG wherein LG is a leaving group and R₂ is asdefined in formula II except methyl and hydrogen, and deprotecting thesilyl-protected primary alcohol:

wherein R₂ is as defined above in the previous disclosure ofintermediates of formula II and Prot^(OH) is a protecting group for OH.

Moreover, this process can further comprise the step of preparing thecompound of formula IIf′ by amidolysis of a compound of formula IIg′:

wherein Prot^(OH) is a protecting group for OH and Ar is a substitutedor unsubstituted aryl group.

Moreover, this process can further comprise the step of preparing acompound of formula IIg′ by reduction of the quinone of formula IIh′followed by protection of the hydroxy groups:

wherein Prot^(OH) is a protecting group for OH and Ar is a substitutedor unsubstituted aryl group.

Moreover, this process can further comprise the step of preparing acompound of formula IIh′ by reaction of cyanosafracin B with asubstituted or unsubstituted arylisocyanate:

wherein Ar is a substituted or unsubstituted aryl group.

The conversion of the methoxyquinone of formula IIa′ to give thecompound of formula II is typically carried out by reaction with asuitable reagent for the deprotection of methoxy groups. Preferredreagent for such reaction is LiI in presence of a base such as anoptionally substituted quinoline or collidine. More preferred base is acollidine. The most preferred base is 2,4,6-collidine.

The protection of the phenol of formula IIb′ to give a compound offormula IIa′ is typically carried out by reaction with a suitablereagent for the protection of phenol groups. Preferred reagents for suchreaction are alkoxymethyl chlorides, alkoxymethylbromides andalkoxyalkoxymethyl chlorides. Alkoxyalkoxymethyl chlorides areparticularly preferred reagents. The most preferred reagent ismethoxyethoxymethyl chloride (MEMCl).

The oxidation of the hydroquinone of formula IIc′ to give a compound offormula IIb′ is carried out by reaction with a suitable oxidizingreagent. Particularly preferred oxidants are oxygen and Pd-oxygen. Themost preferred oxidant is Pd/C-oxygen.

Deprotection of the phenol groups in a compound of formula IId′ to givea hydroquinone of formula IIc′ is carried out under conditions very wellknown by an expert in the art taking into account the structure ofProt^(OH). Particularly preferred conditions are those employed for thedeprotection of allyl protected phenol groups. Most preferred is apalladium catalyzed deprotection in presence of a reducing reagent suchas a trialkyltin hydride.

The preparation of a compound of formula IId′ from a compound of formulaIIe′ is typically carried out by reaction with an amino- andsulphur-protected cysteine amino acid wherein the amino acid isactivated by a coupling agent such as a carbodiimide, a phosphoniumsalt, an uronium salt, a guanidinium salt, an imidazolium derivedreagent, or a triazolium derived reagent. Particularly preferredcoupling agents are carbodiimides. Most preferred coupling agents are1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and itschlorohydrate (EDC.HCl).

The conversion of the primary amine of formula IIf′ to the primaryalcohol of formula IIe′ is typically carried out by reaction with asuitable oxidizing reagent such as an inorganic nitrite, nitrogentetroxide or a nitroferricyanide. More preferred oxidizing reagents areinorganic nitrites. Sodium nitrite is the most preferred oxidizingreagent for this step.

The optional demethylation during the synthesis of a compound of formulaIIe′ typically involves a reaction with a suitable oxidant to providethe corresponding N-oxide. Particularly preferred oxidants for suchreaction are peracids. The most preferred oxidant is m-chloroperbenzoicacid.

The conversion of the compound of formula IIg′ to provide a primaryamine of formula IIf′ is carried out by reaction with a suitableamidolysis reagent. Particularly preferred is the use ofchlorotrimethylsilane/methanol or iodotrimethylsilane as amidolysisreagents.

The reduction of the quinone group in the compound of formula IIh′ istypically carried out using a transition metal catalysed hydrogenationor a reducting reagent such as Na₂S₂O₄. A transition metal catalysedhydrogenation is particularly preferred. The most preferred transitionmetal catalyst is Pd/C. The protection of the hydroxy groups of theintermediate compound to give a compound of formula IIg′ is typicallycarried out by reaction with a suitable reagent for the protection ofphenol groups. Preferred reagents for such reaction are allyl halidesand allyloxycarbonyl halides. More preferred reagents for such reactionsare allyl halides. The most preferred reagent is allyl bromide.

The formation of the urea of formula IIh′ from cyanosafracin B istypically carried out by reaction with an aryl isocyanate. The mostpreferred reagent is phenylisocyanate.

In this process, the use of ether protected OH groups is particularlypreferred. More preferably the ether protected groups are selected fromalkyl silyl ethers, allyl ether, methoxyethoxymethyl ether, andmethoxymethyl ether. The most preferred ether protected OH groups areallyl and methoxyethoxymethyl ether.

In this process, particularly preferred Ar group is phenyl.

In this process, the use of carbamate protected NH groups isparticularly preferred. More preferably carbamate protected amino groupsare selected from allylcarbamate, 2,2,2-trichloroethylcarbamate,benzylcarbamate, 9-fluorenylmethyl-carbamate, and t-butylcarbamate. Themost preferred carbamate protected amino group is t-butylcarbamate.

In this process, the use of thioether protected SH groups isparticularly preferred. More preferably thioether protected SH groupsare substituted or unsubstituted S-9-fluorenylmethyl thioethers. Themost preferred thioether protected SH group is S-9-fluorenylmethyl (Fm)thioether.

In another embodiment, the compounds of formula II can also be obtainedfrom cyanosafracin B following the sequence of reactions indicated inScheme VI:

wherein:Prot₁ ^(OH), Prot^(OH) and R₁ are protecting groups for OH, with theproviso that Prot^(OH) and R₁ are selected to be removed selectively inthe presence of Prot₁ ^(OH) and vice versa.Ar is a substituted or unsubstituted aryl group;Prot^(NH) is a protecting group for amino;Prot^(SH) is a protecting group of SH;and R₂ is as defined above in formula II.

Accordingly, in this embodiment, the process for the synthesis of acompound of formula II comprises the step of deprotecting the Prot₁^(OH)O-groups of a compound of formula IIa′ and oxidating the resultinghydroquinone:

whereinProt₁ ^(OH) and R₁ are protecting groups for OH, with the proviso thatR₁ is selected to be removed selectively in the presence of Prot₁ ^(OH)and vice versa; andR₂, Prot^(NH) and Prot^(SH) are as defined above in the previousdisclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IIa″ by coupling the primary hydroxyl group in acompound of formula IIb″ with a protected cysteine derivative:

whereinProt₁ ^(OH) and R₁ are protecting groups for OH, with the proviso thatR₁ is selected to be removed selectively in the presence of Prot₁ ^(OH)and vice versa; andR₂, Prot^(NH) and Prot^(SH) are as defined above in the previousdisclosure of intermediates of formula II.

Moreover, this process can further comprise the step of preparing thecompound of formula IIb″ by protecting of the phenol of formula IIc″and, optionally, when R₂ in the compound of formula IIb″ is not methyl,followed by protecting the primary alcohol with a silyl protecting groupfor OH, demethylating the NMe group, reacting the resulting secundaryamine with a compound of formula R₂-LG wherein LG is a leaving group andR₂ is as defined in formula II except methyl, and deprotecting thesilyl-protected primary alcohol:

whereinProt₁ ^(OH) and R₁ are protecting groups for OH, with the proviso thatR₁ is selected to be removed selectively in the presence of Prot₁ ^(OH)and vice versa; andR₂ is as defined above in the previous disclosure of intermediates offormula II.

Moreover, this process can further comprise the step of preparing acompound of formula IIc″ by converting the primary amine in a compoundof formula IId″ to a primary alcohol with a suitable oxidizing reagent:

wherein Prot₁ ^(OH) is a protecting group for OH.

Moreover, this process can further comprise the step of preparing thecompound of formula IId″ by amidolysis of a compound of formula IIe″ togive a primary amine:

wherein Prot₁ ^(OH) is a protecting group for OH, Ar is a substituted orunsubstituted aryl group, and X is O or S.

Moreover, this process can further comprise the step of preparing acompound of formula IIe″ by reaction of a compound of formula IIf″ witha substituted or unsubstituted arylisocyanate or arylisothiocyanate:

wherein Prot₁ ^(OH) is a protecting group for OH, Ar is a substituted orunsubstituted aryl group, and X is O or S.

Moreover, this process can further comprise the step of partialdeprotecting a compound of formula IIg″ to provide a compound of formulaIIf″:

whereinProt₁ ^(OH) and Prot^(OH) are protecting groups for OH, with the provisothat Prot^(OH) is selected to be removed selectively in the presence ofProt₁ ^(OH) and vice versa; andProt^(NH) is a protecting group for amino.

Moreover, this process can further comprise the step of preparing acompound of formula IIg″ by reduction of the hydroxyquinone of formulaIIh″ followed by protection of the hydroxy groups:

whereinProt₁ ^(OH) and Prot^(OH) are protecting groups for OH, with the provisothat Prot^(OH) is selected to be removed selectively in the presence ofProt₁ ^(OH) and vice versa; andProt^(NH) is a protecting group for amino.

Moreover, this process can further comprise the step of hydrolysing ordemethylating a methoxyquinone of formula IIi″ to provide a compound offormula IIh″:

wherein Prot^(OH) is a protecting group for OH and Prot^(NH) is aprotecting group for amino.

Moreover, this process can further comprise the step of protecting thephenol of formula IIj″ to provide a compound of formula IIi″:

wherein Prot^(OH) is a protecting group for OH and Prot^(NH) is aprotecting group for amino.

Moreover, this process can further comprise the step of preparing acompound of formula IIj″ by protecting the amino group of cyanosafracinB:

wherein Prot^(NH) is a protecting group for amino.

The deprotection of the compound of formula IIa″ is carried outfollowing standard procedures very well known by a skilled person. Theoxidation of the deprotected intermediate is carried out by reactionwith a suitable oxidizing reagent. Particularly preferred oxidants areoxygen and Pd-oxygen. The most preferred oxidant is Pd/C-oxygen.

The preparation of a compound of formula IIa″ from a compound of formulaIIb″ is typically carried out by reaction with an amino- andsulphur-protected cysteine amino acid wherein the amino acid isactivated by a coupling agent such as a carbodiimide, a phosphoniumsalt, an uronium salt, a guanidinium salt, an imidazolium derivedreagent, or a triazolium derived reagent. Particularly preferredcoupling agents are carbodiimides. Most preferred coupling agents are1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and itschlorohydrate (EDC.HCl).

The protection of the phenol of formula IIc″ to give a compound offormula IIb″ is typically carried out by reaction with a suitablereagent for the protection of phenol groups. Preferred reagents for suchreaction are alkoxymethyl chlorides, alkoxymethylbromides andalkoxyalkoxymethyl chlorides. Alkoxyalkoxymethyl chlorides areparticularly preferred reagents. The most preferred reagent ismethoxyethoxymethyl chloride (MEMCl). The optional demethylation duringthe synthesis of a compound of formula IIb″ typically involves areaction with a suitable oxidant to provide the corresponding N-oxide.Particularly preferred oxidants for such reaction are peracids. The mostpreferred oxidant is m-chloroperbenzoic acid.

The conversion of the primary amine of formula IId″ to provide theprimary alcohol of formula IIc″ is typically carried out by reactionwith a suitable oxidizing reagent such as an inorganic nitrite, nitrogentetroxide or a nitroferricyanide. More preferred oxidizing reagents areinorganic nitrites. Sodium nitrite is the most preferred oxidizingreagent for this step.

The conversion of the compound of formula IIe″ to a primary amine offormula IId″ is typically carried out by reaction with a suitableamidolysis reagent. Particularly preferred is the use ofchlorotrimethylsilane/methanol or iodotrimethylsilane as amidolysisreagents.

The formation of a urea or thiourea of formula IIe″ from a compound offormula IIf″ is typically carried out by reaction with an arylisocyanate or with an arylisothiocyanate. Particularly preferredreagents for such reaction are arylisothiocyanates. The most preferredreagent is phenylisothiocyanate.

The partial deprotection of the compound of formula IIg″ to provide acompound of formula IIf″ is preferably carried out in a one-pot stepusing acidic conditions.

The reduction of the hydroxyquinone of formula IIh″ is typically carriedout using a transition metal catalysed hydrogenation or a reductingreagent such as Na₂S₂O₄. A transition metal catalysed hydrogenation isparticularly preferred. The most preferred transition metal catalyst isPd/C. The hydroxy groups in the intermediate hydroquinone are protectedto provide a compound of formula IIg″. Protection of the hydroxy groupsis typically carried out by reaction with a suitable reagent for theprotection of phenol groups. Particularly preferred protecting groupsfor this step are allyl and allyloxycarbonyl groups. The most preferredprotecting group is allyl.

The conversion of the methoxyquinone of formula IIi″ to give thehydroxyquinone of formula IIh″ is typically carried out by reaction witha suitable reagent for the deprotection of methoxy groups or by reactionwith a hydroxide. Preferred reagents for such reaction are a hydroxideor LiI in presence of a base. More preferably the reaction is carriedout with an alkaline hydroxide. The most preferred alkaline hydroxide isLiOH.

The protection of the phenol of formula IIj″ to give a compound offormula IIi″ is typically carried out by reaction with a suitablereagent for the protection of phenol groups. Preferred reagents for suchreaction are alkoxymethyl chlorides, alkoxymethylbromides andalkoxyalkoxymethyl chlorides. Alkoxyalkoxymethyl chlorides areparticularly preferred reagents. The most preferred reagent ismethoxyethoxymethyl chloride (MEMCl).

The protection of Cyanosafracin B to give a compound of formula IIj″ istypically carried out by reaction with a suitable reagent for theprotection of amino groups. Preferred reagents for such reaction aredicarbonates and alkoxycarbonylchlorides. Dicarbonates are particularlypreferred reagents. The most preferred reagent is di-tert-butyldicarbonate (Boc₂O).

In this process, particularly preferred Prot^(OH) groups are those thattogether with the O atom to which they are attached form an ether group.More preferably Prot^(OH) groups are methoxyethoxymethyl andmethoxymethyl. The most preferred Prot^(OH) group ismethoxyethoxymethyl. Particularly preferred Prot₁ ^(OH) groups are thosethat together with the O atom to which they are attached form an etheror a carbonate groups. More preferably Prot₁ ^(OH) groups are allyl andallyloxycarbonyl. The most preferred Prot₁ ^(OH) group is allyl.

In this process, the most preferred Ar group is phenyl.

In this process, the use of carbamate protected NH groups isparticularly preferred. More preferably carbamate protected amino groupsare selected from allylcarbamate, 2,2,2-trichloroethylcarbamate,benzylcarbamate, 9-fluorenylmethyl-carbamate, and t-butylcarbamate. Themost preferred carbamate protected amino group is t-butylcarbamate.

In this process, the use of thioether protected SH groups isparticularly preferred. More preferably thioether protected SH groupsare substituted or unsubstituted S-9-fluorenylmethyl thioethers. Themost preferred thioether protected SH group is S-9-fluorenylmethyl (Fm)thioether.

Examples of suitable starting materials for the synthesis of compoundsof formula II include:

(a) Saframycin A, saframycin H, saframycin S, saframycin Y₃, saframycinY_(d1), saframycin A_(d1), saframycin Y_(d2), saframycin AH₂, saframycinAH₂Ac, saframycin AH₁, and saframycin AH₁Ac of formula:

Compound R₃ R_(15a) R_(15b) R_(15c) Saframycin A CN O Me Saframycin H CNOH CH₂COMe Me Saframycin S OH O Me Saframycin Y₃ CN NH₂ H Me SaframycinY_(d1) CN NH₂ H C₂H₅ Saframycin A_(d1) CN O C₂H₅ Saframycin Y_(d2) CNNH₂ H H Saframycin AH₂ CN H^(a) OH^(a) Me Saframycin AH₂Ac CN H OAc MeSaframycin AH₁, CN OH^(a) H^(a) Me Saframycin AH₁Ac CN OAc H Me^(a)Assignments are interchangeable.

(b) Safracin B and cyanosafracin B of formula:

Compound R₃ R_(15a) R_(15b) R_(15c) Safracin B OH NH₂ H Me CyanosafracinB CN NH₂ H Me

(c) Jorumycin, cyanojorumycin, renieramycin E, jorunnamycin A, andjorunnamycin C of formula:

Compound R₃ R Jorumycin OH COMe Cyanojorumycin CN COMe Renieramycin E OHCO—C(CH₃)═CH—CH₃ Jorunnamycin A CN H Jorunnamycin C CN COCH₂CH₃that are disclosed in Charupant, K. et. al. Bioorganic MedicinalChemistry, 2009, 17, 4548-4558.

d) Renieramycin T (described in Daikuhara, N. et. al. TetrahedronLetters, 2009, 50, 4276-4278)

and

e) Saframycin R

The most preferred starting material for the synthesis of compounds offormula II is cyanosafracin B of formula:

This invention also relates to the use of intermediates of formula II inthe manufacture of compounds of formula I, and in particular in themanufacture of:

In additional preferred embodiments, the preferences described above forthe different groups and substituents are combined. The presentinvention is also directed to such combinations of preferred groups andsubstitutions in the formulae above.

EXAMPLES Example 1 Synthesis of Intermediate 10

Route A

Scheme VII provides an example of the synthesis of intermediate 10 (acompound of formula II).

Synthesis of Intermediate 2a

A mixture of cyanosafracin B (1) (3.06 g, 5.6 mmol) and phenylisocyanate (0.6 mL, 5.6 mmol) in CH₂Cl₂ (29 mL, 5.2 mL/mmol) was stirredfor 4 h at 23° C. The reaction mixture was concentrated under vacuum andthe crude was purified by column flash chromatography over SiO₂ elutedwith Hexane:EtOAc (from 60:40 to 20:80) to give pure 2a (3.7 g, 100%yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.23-6.95 (m, 6H), 6.47 (s, 1H), 6.37 (s,1H), 5.51 (d, 1H, J=7.7 Hz), 5.40 (m, 1H), 4.18 (s, 1H), 4.02 (m, 1H),3.86 (s, 3H), 3.76 (m, 1H), 3.71 (s, 3H), 3.35-3.02 (m, 6H), 2.48-2.41(d, 1H, J=18.0 Hz), 2.35 (s, 3H), 2.24 (s, 3H), 1.95-1.85 (m, 1H), 1.00(d, 3H, J=6.0 Hz).

¹³C-NMR (CDCl₃, 75 MHz): δ 185.6, 181.1, 173.9, 155.6, 154.7, 147.4,143.6, 142.4, 138.6, 135.0, 130.5, 129.5, 129.0, 128.6, 123.0, 120.2,119.7, 117.5, 117.0, 60.8, 60.5, 59.0, 56.0, 55.7, 55.1, 54.8, 49.4,41.7, 41.4, 25.5, 24.2, 18.6, 15.7, 8.6.

MS (ES): m/z 669.2 [M+1]⁺.

Synthesis of Intermediate 3a

A suspension of 2a (450 mg, 0.67 mmol) and Pd on carbon (90 mg, 10%) inanhydrous DMF (10 mL, 15 mL/mmol) was degasified under vacuum andstirred under an hydrogen atmosphere for 2 h at 23° C. The reactionmixture was filtered through a 0.45 μm PTFE filter over anhydrous Cs₂CO₃(1.3 g, 4.0 mmol), washed with DMF (5 mL), and allyl bromide (1.7 mL, 20mmol) was added at 23° C. The reaction mixture was stirred for 4 h at23° C. and filtered through Celite®. An aqueous saturated solution ofNaCl was added to the filtered solution which was extracted with CH₂Cl₂.The combined organic layers were dried over Na₂SO₄, filtered, andconcentrated under vacuum. The crude was purified by column flashchromatography over SiO₂ eluted with CH₂Cl₂:EtOAc (40:60) to afford pure3a (296 mg, 56% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.31-6.87 (m, 5H), 6.62 (s, 1H), 6.24 (d, 1H,J=7.8 Hz), 6.13-6.00 (m, 3H), 5.86 (m, 1H), 5.43 (s, 1H), 5.37 (s, 2H),5.31-5.19 (m, 4H), 4.73 (dd, 1H, J=12.3 and 5.7 Hz), 4.50 (m, 1H), 4.27(m, 2H), 4.11 (m, 3H), 3.92 (m, 1H), 3.79 (s, 3H), 3.76 (m, 1H), 3.61(s, 3H), 3.50 (m, 1H), 3.20 (m, 2H), 3.0 (dd, 2H, J=18.0 and 8.4 Hz),2.45 (d, 1H, J=18.0 Hz), 2.28 (s, 3H), 2.18 (s, 3H), 2.12 (s, 3H), 1.86(m, 1H), 1.03 (d, 3H, J=9 Hz).

¹³C-NMR (CDCl₃, 75 MHz): δ 173.8, 154.5, 150.5, 150.4, 149.7, 149.1,144.2, 139.0, 134.1, 133.8, 130.9, 129.6, 128.6, 125.0, 124.9, 124.5,123.7, 122.2, 119.1, 118.0, 117.8, 117.7, 117.6, 74.0, 73.8, 73.3, 60.2,60.0, 56.7, 56.4, 55.1, 49.3, 43.6, 41.6, 26.3, 25.5, 19.2, 15.8, 9.6, 6carbon signals overlap.

MS (ES): m/z 791.3 [M+1]⁺.

Synthesis of Intermediate 4a

A solution of 3a (90 mg, 0.13 mmol) and TMSCl (0.2 mL, 1.6 mmol) in MeOH(2.45 mL, 18.8 mL/mmol) was stirred for 6 h at 70° C. The reactionmixture was cooled to 23° C. and concentrated under vacuum. The crudeobtained was diluted with EtOAc and acidified with HCl 1M until acid pH.The aqueous layer was washed with EtOAc (3×), basified with K₂CO₃ untilbasic pH, and extracted with CH₂Cl₂. The combined organic layers weredried over Na₂SO₄, filtered, and concentrated under vacuum to give crude4a (61 mg, 76% yield) which was used in the next step without furtherpurification.

¹H-NMR (CDCl₃, 300 MHz): δ 6.69 (s, 1H), 6.13-6.04 (m, 3H), 5.44-5.20(m, 3H), 4.71 (dd, 1H, J=12.3 and 5.4 Hz), 4.59-4.41 (m, 2H), 4.33-4.01(m, 8H), 3.76 (s, 6H), 3.34-3.05 (m, 4H), 2.72-2.50 (m, 3H), 2.34 (s,3H), 2.21 (s, 3H), 2.16 (s, 3H), 1.76 (dd, 1H, J=15.6 and 12.0 Hz).

¹³C-NMR (CDCl₃, 75 MHz): δ 150.1, 149.9, 149.5, 149.0, 144.4, 134.2,134.2, 133.8, 130.8, 129.9, 129.1, 128.2, 125.8, 125.2, 124.7, 124.2,123.8, 118.0, 74.0, 73.7, 73.5, 60.7, 60.2, 59.9, 58.9, 57.2, 56.6,55.4, 46.5, 41.7, 29.7, 26.5, 25.8, 15.8, 9.6.

MS (ES): m/z 601.3 [M+1]⁺, 623.2 [M+23]⁺.

Synthesis of Intermediate 5a

To a mixture of 4a (6.89 g, 11.5 mmol) and H₃PO₄:Na₂HPO₄ aqueoussolution (35 mL, 0.018 g H₃PO₄:0.186 g Na₂HPO₄ per mL of H₂O) in CH₂Cl₂(69 mL, 6 mL/mmol), an aqueous solution of NaNO₂ (7.9 mL, 23.0 mmol,20%) was portion wise added over 1 h at 23° C. The reaction mixture wasstirred overnight at 23° C., diluted with H₂O, and extracted withCH₂Cl₂. The combined organic layers were dried over Na₂SO₄, filtered,and concentrated under vacuum. The crude was purified by column flashchromatography over SiO₂ eluted with CH₂Cl₂:EtOAc (40:60) to afford pure5a (4.62 g, 67% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 6.72 (s, 1H), 6.16-6.05 (m, 3H), 5.44-5.2 (m,6H), 4.71 (dd, 1H, J=12.3 and 5.4 Hz), 4.60-4.44 (m, 2H), 4.34-4.04 (m,6H), 3.76 (s, 3H), 3.75 (s, 3H), 3.60-3.56 (m, 1H), 3.35 (d, 1H, J=7.5Hz), 3.28-3.22 (m, 3H), 3.13 (dd, 1H, J=18.0 and 7.5 Hz), 2.52 (d, 1H,J=18.0 Hz), 2.37 (s, 3H), 2.21 (s, 3H), 2.16 (s, 3H), 1.90 (dd, 1H,J=8.5 and 4.0 Hz), 1.76 (dd, 1H, J=16.0 and 12.5 Hz).

¹³C-NMR (CDCl₃, 75 MHz): δ 150.1, 149.7, 149.6, 149.2, 144.5, 134.1,133.8, 130.9, 129.5, 125.6, 124.8, 124.6, 124.2, 123.7, 117.8, 117.6,117.5, 73.9, 73.7, 73.5, 65.7, 60.8, 60.1, 59.8, 58.6, 57.2, 56.7, 55.4,41.7, 26.2, 25.8, 15.7, 9.5, two carbon signals overlap.

MS (ES): m/z 602.3 [M+1]⁺, 624.2 [M+23]⁺.

Synthesis of Intermediate 6a

To a solution of 5a (4.65 g, 7.7 mmol) and Boc-L-Cys(Fm)-OH (6.1 g, 15.4mmol) in CH₂Cl₂ (264 mL, 34 mL/mmol), DIPEA (2.67 mL, 15.4 mmol),EDC.HCl (4.41 g, 23.0 mmol) and DMAP (0.938 g, 7.7 mmol) were added at23° C. The reaction mixture was stirred for 1.5 h at 23° C., dilutedwith CH₂Cl₂, and washed with an aqueous saturated solution of NaHCO₃.The combined organic layers were dried over Na₂SO₄, filtered, andconcentrated under vacuum. The crude was purified by column flashchromatography over SiO₂ eluted with Hexane:EtOAc (from 90:10 to 80:20)to afford pure 6a (7.12 g, 94% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.75-7.28 (m, 8H), 6.60 (s, 1H), 6.13-5.99(m, 3H), 5.42-5.16 (m, 7H), 4.73-4.67 (m, 1H), 4.56-4.51 (m, 1H),4.43-3.80 (m, 10H), 3.76 (s, 3H), 3.73 (s, 3H), 3.28-2.81 (m, 7H),2.61-2.48 (m, 2H), 2.28 (s, 3H), 2.19 (s, 3H), 2.13 (s, 3H), 1.77-1.68(m, 1H), 1.45 (s, 9H).

¹³C-NMR (CDCl₃, 75 MHz): δ 170.9, 155.2, 150.5, 150.0, 149.7, 148.9,146.0, 144.9, 141.2, 134.5, 134.2, 133.9, 130.7, 130.6, 127.8, 127.2,125.5, 125.0, 124.8, 124.4, 123.8, 120.1, 118.4, 118.2, 117.9, 117.7,80.34, 74.3, 74.1, 73.6, 69.0, 61.6, 60.4, 60.2, 57.4, 57.2, 56.5, 55.7,53.6, 47.0, 41.9, 37.3, 35.6, 29.9, 28.6, 26.6, 25.8, 15.9, 9.8.

MS (ES): m/z 983.3 [M+1]⁺.

Synthesis of Intermediate 7a

To a suspension of 6a (7.12 g, 7.2 mmol) and PdCl₂(Ph₃P)₂ (814 mg, 1.16mmol) in CH₂Cl₂ (132 mL, 18 mL/mmol), AcOH (4.14 mL, 72.4 mmol) andBu₃SnH (11.68 mL, 43.4 mmol) were added at 23° C. The reaction mixturewas stirred for 1 h at 23° C., loaded into a column flash chromatographyover SiO₂ and eluted with Hexane:EtOAc (from 80:20 to 60:40) to affordpure 7a (6.28 g, 100% yield).

¹H-NMR (CD₃OD, 300 MHz): δ 7.76-7.56 (m, 4H), 7.37-7.23 (m, 4H),6.44-6.34 (m, 1H), 4.28-4.01 (m, 6H), 3.85-3.80 (m, 1H), 3.68 (s, 3H),3.62 (s, 3H), 3.25 (m, 1H), 3.07-2.86 (m, 5H), 2.71-2.54 (m, 2H),2.41-2.34 (m, 1H), 2.21 (s, 3H), 2.17 (s, 3H), 2.08 (s, 3H), 1.84 (m,1H), 1.41 (s, 9H).

¹³C-NMR (CD₃OD, 75 MHz): δ 171.1, 147.6, 146.2, 144.3, 143.9, 143.6,141.2, 139.9, 131.2, 129.3, 127.4, 126.9, 124.9, 124.8, 120.9, 120.2,119.6, 118.3, 117.6, 79.6, 67.3, 61.1, 59.7, 57.8, 56.9, 56.6, 55.7,53.8, 40.6, 36.5, 34.5, 27.5, 25.9, 25.5, 14.9, 8.6, twelve carbonsignals overlap.

MS (ES): m/z 863.0 [M+1]⁺.

Synthesis of Intermediate 8a

A suspension of 7a (1.7 g, 2.0 mmol) and Pd on carbon (855 mg, 10%) inMeOH (50 mL, 25.5 mL/mmol) was stirred for 24 h under an air atmosphereat 23° C. The reaction mixture was filtered through Celite®, washed withCH₂Cl₂, and concentrated. The crude was purified by column flashchromatography over SiO₂ eluted with Hexane:EtOAc (from 70:30 to 60:40)to afford pure 8a (1.41 g, 82% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.74-7.58 (m, 4H), 7.4-7.25 (m, 4H), 6.37 (s,1H), 5.81 (s, 1H), 4.90 (d, 1H, J=8.4 Hz), 4.57 (m, 1H), 4.13-4.01 (m,5H), 3.95 (s, 3H), 3.70 (s, 3H), 3.31 (d, 1H), J=8.1 Hz), 3.15-2.88 (m,5H), 2.53 (d, 1H, J=18.6 Hz), 2.39 (m, 1H), 2.26 (s, 3H), 2.21 (s, 3H),1.85 (s, 3H), 1.69 (m, 1H), 1.38 (s, 9H).

¹³C-NMR (CDCl₃, 75 MHz): δ 185.6, 181.2, 170.4, 155.5, 154.8, 146.8,145.8, 142.9, 142.8, 140.9, 140.8, 134.8, 131.1, 130.9, 129.1, 128.6,127.5, 126.9, 124.9, 124.8, 120.7, 119.8, 117.4, 116.1, 79.8, 63.1,61.0, 60.8, 59.1, 56.4, 55.8, 55.4, 55.1, 52.7, 46.9, 46.6, 41.7, 41.6,36.9, 36.6, 34.7, 34.4, 29.6, 28.2, 24.7, 15.8, 8.7.

MS (ES): m/z 861.2 [M+1]⁺.

Synthesis of Intermediate 9a

To a solution of 8a (4.5 g, 5.2 mmol) in CH₃CN (166 mL, 32 mL/mmol),DIPEA (18.2 mL, 104 mmol), MEMCl (8.86 mL, 78 mmol) and catalytic DMAPwere added at 23° C. The reaction mixture was stirred for 5 h at 23° C.,diluted with CH₂Cl₂, and washed with HCl 1M and an aqueous saturatedsolution of NaHCO₃. The combined organic layers were dried over Na₂SO₄,filtered, and concentrated under vacuum. The crude was purified bycolumn flash chromatography over SiO₂ eluted with CH₂Cl₂:EtOAc (from90:10 to 70:30) to afford pure 9a (2.51 g, 51% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.73-7.58 (m, 4H), 7.40-7.29 (m, 4H), 6.56(s, 1H), 5.28-5.14 (m, 2H), 4.94 (m, 1H), 4.48 (m, 1H), 4.20 (bs, 1H),4.09-3.94 (m, 5H), 3.94 (s, 3H), 3.80 (m, 1H), 3.68 (s, 3H), 3.58 (t,2H, J=4.8 Hz), 3.38 (s, 3H), 3.31 (m, 1H), 3.14-2.87 (m, 6H), 2.53 (d,1H, J=18.6 Hz), 2.40 (m, 1H), 2.28 (s, 3H), 2.16 (s, 3H), 1.83 (s, 3H),1.56 (m, 1H), 1.38 (s, 9H).

¹³C-NMR (CDCl₃, 75 MHz): δ 185.5, 181.1, 170.4, 155.5, 154.7, 148.7,148.2, 145.7, 142.9, 140.9, 140.8, 134.7, 130.9, 130.3, 128.5, 127.5,127.0, 124.8, 124.7, 123.1, 119.8, 117.4, 98.1, 79.9, 71.6, 69.3, 63.3,61.0, 60.0, 59.2, 58.9, 56.3, 56.1, 55.2, 55.0, 52.8, 46.6, 41.4, 37.3,36.6, 34.6, 28.2, 24.8, 24.6, 15.7, 8.6.

MS (ES): m/z 949.2 [M+1]⁺.

Synthesis of Intermediate 10

A solution of 9a (194 mg, 0.2 mmol) in 2,4,6-collidine (4.3 mL, 21.5mL/mmol) was degasified and LiI (401 mg, 3.0 mmol) was added at 23° C.The reaction mixture was stirred for 24 h at 23° C., diluted withCH₂Cl₂, and washed with HCl 1M. The combined organic layers were driedover Na₂SO₄, filtered, and concentrated under vacuum. The crude waspurified by column flash chromatography over SiO₂ eluted withHexane:EtOAc (from 50:50 to 40:60) to afford pure 10 (115 mg, 57%yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.74-7.57 (m, 4H), 7.40-7.28 (m, 4H), 6.58(s, 1H), 5.29-5.14 (m, 2H), 5.00 (m, 1H), 4.43 (m, 1H), 4.21 (bs, 1H),4.09-3.79 (m, 8H), 3.69 (s, 3H), 3.58 (t, 2H, J=4.8 Hz), 3.39 (s, 3H),3.32 (m, 1H), 3.14-2.88 (m, 5H), 2.53 (d, 1H, J=18.6 Hz), 2.38 (m, 1H),2.28 (s, 3H), 2.17 (s, 3H), 1.85 (s, 3H), 1.39 (s, 9H).

¹³C-NMR (CDCl₃, 75 MHz): δ 184.9, 181.1, 170.6, 154.7, 151.0, 148.8,148.3, 145.7, 145.6, 140.9, 132.7, 131.1, 130.3, 127.6, 127.0, 124.8,123.1, 119.9, 117.4, 117.1, 98.2, 80.2, 71.7, 69.3, 63.1, 60.0, 59.3,59.0, 56.1, 55.8, 55.3, 55.1, 52.8, 46.7, 41.4, 36.7, 34.8, 29.7, 28.2,25.2, 24.8, 15.8, 8.0.

MS (ES): m/z 935.3 [M+1]⁺.

Route B

Scheme VIII provides another example of the synthesis of intermediate10.

Synthesis of Intermediate 5b

Compound 4b was obtained as disclosed in WO 00/69862. A suspension of 4b(1.14 g, 1.68 mmol) and 10% Palladium on Carbon (228 mg, 20% w/w) inanhydrous DMF (15 mL) was stirred for 2 h at 23° C. under a H₂atmosphere. The reaction mixture was filtered through Celite® to a flaskcontaining anhydrous Cs₂CO₃ (3.28 g, 10.1 mmol), washed with DMF (10mL), and allyl bromide (2.9 mL, 33.6 mol) added at 23° C. The reactionmixture was stirred for 3 h at 23° C., was filtered through Celite®, andwashed with CH₂Cl₂. The combined organic layers were washed with anaqueous saturated solution of NaCl, dried over anhydrous Na₂SO₄,filtered, and concentrated to dryness in vacuo by rotary evaporation.The resulting crude was purified by column flash chromatography overSiO₂ eluted with Hexane:EtOAc (from 70:30 to 50:50) to afford pure 5b(384 mg, 29% yield).

¹H-NMR (300 MHz, CDCl₃): δ 6.70 (s, 1H), 6.05 (m, 3H), 5.51 (bs, 1H),5.38-5.17 (m, 6H), 5.11 (s, 2H), 4.88, (bs, 1H), 4.62-463 (m, 3H),4.30-4.01 (m, 6H), 3.73 (s, 3H), 3.56 (s, 3H), 3.52-3.16 (m, 6H), 3.04(dd, J=18.0 and 7.9 Hz, 1H), 2.56 (d, J=18.0 Hz, 1H), 2.31 (s, 3H), 2.25(s, 3H), 2.14 (s, 3H), 1.82 (m, 1H), 1.30 (s, 9H), 0.98 (d, J=6.9 Hz,1H).

¹³C-NMR (75 MHz, CDCl₃): δ 171.8, 154.8, 150.1, 148.7, 148.5, 148.4,144.5, 133.9, 133.8, 133.8, 130.9, 130.2, 125.1, 125.0, 124.8, 124.6,124.0, 118.0, 117.9, 117.5, 117.2, 99.2, 79.3, 77.2, 73.7, 73.6, 73.4,59.9, 59.7, 57.7, 57.7, 57.2, 56.7, 56.1, 55.1, 49.6, 43.0, 41.5, 28.1,26.3, 25.4, 18.7, 15.7, 9.8.

MS (ES): m/z 802.4 [M+1]⁺.

Synthesis of Intermediate 6b

To a solution of 5b (370 mg, 0.46 mmol) in CH₂Cl₂ (7.6 mL), TFA (1.42mL, 18.4 mmol) was added at 23° C. The reaction mixture was stirred for1.5 h at 23° C. and concentrated to dryness in vacuo by rotaryevaporation. The crude obtained was dissolved with CH₂Cl₂, neutralizedby addition of an aqueous saturated solution of K₂CO₃ until basic pH,and extracted with CH₂Cl₂. The combined organic layers were dried overanhydrous Na₂SO₄, filtered, and concentrated to dryness in vacuo byrotary evaporation to give crude 6b (340 mg, 100% yield) which was usedin the next step without further purification

¹H-NMR (300 MHz, CDCl₃): δ 6.55 (m, 1H), 6.49 (s, 1H), 6.15-5.99 (m,3H), 5.37-5.11 (m, 7H), 4.60-4.03 (m, 9H), 3.76 (s, 3H), 3.46-3.17 (m,5H), 3.04-2.87 (m, 3H), 2.60 (d, J=18.3 Hz, 1H), 2.30 (s, 3H), 2.25 (s,3H), 2.16 (s, 3H), 1.96-1.88 (m, 1H).

MS (ES): m/z 658.3 [M+1]⁺.

Synthesis of Intermediate 7b

A solution of 6b (236 mg, 0.3 mmol) and phenyl isothiocyanate (0.21 mL,1.8 mmol) in CH₂Cl₂ (65.7 mL) was stirred for 2 h at 23° C. The reactionmixture was loaded into a column flash chromatography over SiO₂ elutedwith Hexane:EtOAc (from 90:10 to 40:60) to afford pure 7b (220 mg, 92%yield).

¹H-NMR (300 MHz, CDCl₃): δ 7.65 (s, 1H), 7.39 (t, J=7.5 Hz, 2H), 7.15(d, J=7.5 Hz, 2H), 6.93 (d, J=7.5 Hz, 1H), 6.30 (s, 1H), 6.13-5.96 (m,3H), 5.79 (s, 1H), 5.45-5.11 (m, 8H), 4.62-4.34 (m, 3H), 4.34-3.99 (m,8H), 3.77 (s, 3H), 3.56 (m, 2H), 3.35-3.16 (m, 4H), 3.0 (dd, J=18.0 and7.9 Hz, 1H), 2.50 (d, J=18.0 Hz, 1H), 2.28 (s, 3H), 2.19 (s, 3H), 2.14(s, 3H), 1.84 (m, 1H), 0.96 (d, J=6.9 Hz, 1H).

Synthesis of Intermediate 8b

To a solution of 7b (295 mg, 0.32 mmol) in MeOH (2.5 mL),chlorotrimethylsilane (0.24 mL, 1.92 mmol) was added at 23° C. Thereaction mixture was stirred for 1.5 h at 23° C. and concentrated todryness in vacuo by rotary evaporation. The crude obtained was dissolvedwith EtOAc, HCl 1M was added until acid pH, and extracted with EtOAc.The aqueous layer was basified with solid K₂CO₃ and extracted withCH₂Cl₂. The combined organic layers were dried over anhydrous Na₂SO₄,filtered, and concentrated to dryness in vacuo by rotary evaporation toobtain crude 8b (196 mg, 90% yield) which was used in the next stepwithout further purification.

¹H-NMR (300 MHz, CDCl₃): δ 6.52 (s, 1H), 6.15-5.97 (m, 3H), 5.43-5.19(m, 6H), 4.63-4.42 (m, 3H), 4.31-4.10 (m, 7H), 3.76 (s, 3H), 3.34-3.22(m, 3H), 3.10 (dd, J=18.2 and 7.6 Hz, 1H), 2.80 (m, 1H), 2.62 (d, J=17.7Hz, 1H), 2.35 (s, 3H), 2.26 (s, 3H), 2.17 (s, 3H), 1.77 (m, 1H).

¹³C-NMR (75 MHz, CDCl₃): δ 150.7, 149.0, 146.8, 144.6, 143.2, 134.2,134.0, 130.8, 129.4, 125.3, 121.3, 118.6, 118.2, 117.8, 117.8, 117.0,74.3, 73.7, 61.0, 60.7, 57.5, 56.8, 55.7, 46.3, 41.9, 29.9, 26.5, 25.8,16.1, 10.3, four carbon signals overlap.

Synthesis of Intermediate 9b

To a mixture of 8b (120 mg, 0.21 mmol) and H₃PO₄:Na₂HPO₄ solution (0.63mL, 8.6 mL H₂O:0.151 g H₃PO₄:1.6 g Na₂HPO₄) in CH₂Cl₂ (1.3 mL), anaqueous solution of NaNO₂ (7.9 mL, 0.31 mmol, 20%) was slowly added over1 h at 23° C. The reaction mixture was stirred for 18 h at 23° C.,diluted with H₂O, and extracted with CH₂Cl₂. The combined organic layerswere dried over anhydrous Na₂SO₄, filtered, and concentrated to drynessin vacuo by rotary evaporation. The crude was purified by column flashchromatography over SiO₂ eluted with Hexane:EtOAc (from 70:30 to 60:40)to afford pure 9b (68 mg, 54% yield).

¹H-NMR (300 MHz, CDCl₃): δ 6.49 (s, 1H), 6.16-5.97 (m, 3H), 5.79 (s,1H), 5.44-5.18 (m, 6H), 4.61-4.41 (m, 3H), 4.31-4.18 (m, 4H), 4.05 (m,2H), 3.73 (s, 3H), 3.59 (m, 1H), 3.35-3.08 (m, 6H), 2.53 (d, J=18.0 Hz,1H), 2.36 (s, 3H), 2.24 (s, 3H), 2.15 (s, 3H), 1.84 (m, 1H).

¹³C-NMR (75 MHz, CDCl₃): δ 150.1, 148.5, 146.6, 144.5, 143.0, 134.0,133.9, 130.3, 129.0, 125.7, 125.0, 124.4, 120.7, 117.9, 117.5, 117.4,117.3, 116.8, 77.2, 74.0, 73.6, 73.5, 65.9, 60.8, 60.7, 58.5, 57.1,56.7, 55.4, 41.6, 26.0, 25.8, 15.7, 9.9.

Synthesis of Intermediate 10b

To a solution of 9b (20 mg, 0.033 mmol) in THF (0.2 mL),1-chloromethoxy-2-methoxyethane (4.4 μL, 0.039 mmol) and NaH (1.5 mg,0.038 mmol, 60% dispersion in mineral oil) were added at 0° C. Thereaction mixture was stirred for 1 h at 23° C., catalytic amount of NaHwas added and the stirring was maintained for an additional 1 h at 23°C. Then the reaction mixture was diluted with an aqueous saturatedsolution of NaCl, and extracted with CH₂Cl₂. The combined organic layerswere dried over anhydrous Na₂SO₄, filtered, and concentrated to drynessin vacuo by rotary evaporation. The crude was purified by column flashchromatography over SiO₂ eluted with Hexane:EtOAc (from 70:30 to 60:40)to afford pure 10b (16.5 mg, 75% yield).

¹H-NMR (300 MHz, CDCl₃): δ 6.72 (s, 1H), 6.16-5.97 (m, 3H), 5.47-5.16(m, 8H), 4.61-4.41 (m, 3H), 4.30-4.19 (m, 4H), 4.05-3.81 (m, 4H), 3.68(s, 3H), 3.59 (m, 4H), 3.39 (s, 3H), 3.34-3.10 (m, 5H), 2.50 (d, J=18.0Hz, 1H), 2.37 (s, 3H), 2.20 (s, 3H), 2.14 (s, 3H), 1.78 (m, 1H).

MS (ES): m/z 676.2 [M+1]⁺.

Synthesis of Intermediate 11b

To a solution of 10b (75 mg, 0.11 mmol) and Boc-L-Cys(Fm)-OH (88 mg,0.22 mmol) in CH₂Cl₂ (2.3 mL), DIPEA (38 μL, 0.22 mmol),N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (63 mg, 0.33mmol) and DMAP (13 mg, 0.11 mmol) were added at 23° C. The reactionmixture was stirred for 3 h at 23° C., diluted with CH₂Cl₂, and washedwith an aqueous saturated solution of NaHCO₃. The combined organiclayers were dried over anhydrous Na₂SO₄, filtered, and concentrated todryness in vacuo by rotary evaporation. The crude was purified by columnflash chromatography over SiO₂ eluted with Hexane:EtOAc (from 70:30 to60:40) to afford pure 11b (81 mg, 70% yield).

¹H-NMR (300 MHz, CDCl₃): δ 7.76-7.61 (m, 4H), 7.38-7.26 (m, 4H), 6.60(s, 1H), 6.12-5.96 (m, 3H), 5.44-5.13 (m, 8H), 4.53-3.82 (m, 13H), 3.70(s, 3H), 3.57 (m, 2H), 3.38 (s, 3H), 3.25-2.83 (m, 8H), 2.63-2.48 (m,2H), 2.30 (s, 3H), 2.17-2.14 (m, 6H), 1.72 (m, 1H), 1.44 (s, 9H).

¹³C-NMR (75 MHz, CDCl₃): δ 170.6, 154.9, 150.2, 150.1, 148.5, 148.4,148.2, 145.7, 144.8, 144.7, 140.9, 140.9, 134.0, 133.84, 133.76, 130.5,127.6, 127.0, 125.3, 124.9, 124.8, 124.1, 123.7, 119.9, 118.2, 118.0,117.5, 117.4, 117.3, 98.2, 80.1, 77.2, 73.9, 73.4, 71.7, 69.3, 61.4,59.7, 59.0, 57.2, 56.9, 56.3, 55.4, 53.4, 46.9, 46.8, 41.5, 37.0, 35.4,29.7, 28.3, 26.2, 25.5, 23.6, 15.7, 9.9.

Synthesis of Intermediate 10 from Intermediate 11b

To a suspension of 11b (13 mg, 0.013 mmol) and PdCl₂(Ph₃P)₂ (1.5 mg,0.0021 mmol) in CH₂Cl₂ (0.3 mL), AcOH (7 μL, 0.13 mmol) and n-Bu₃SnH (21μL, 0.078 mmol) were added at 23° C. The reaction mixture was stirredfor 45 minutes at 23° C. and loaded into a column flash chromatographyover SiO₂ eluted with different mixtures of Hexane:EtOAc (90:10, 70:30,40:60) to afford pure 10 (10.4 mg, 90% yield).

¹H-NMR (CDCl₃, 300 MHz): δ 7.74-7.57 (m, 4H), 7.40-7.28 (m, 4H), 6.58(s, 1H), 5.29-5.14 (m, 2H), 5.00 (m, 1H), 4.43 (m, 1H), 4.21 (bs, 1H),4.09-3.79 (m, 8H), 3.69 (s, 3H), 3.58 (t, 2H, J=4.8 Hz), 3.39 (s, 3H),3.32 (m, 1H), 3.14-2.88 (m, 5H), 2.53 (d, 1H, J=18.6 Hz), 2.38 (m, 1H),2.28 (s, 3H), 2.17 (s, 3H), 1.85 (s, 3H), 1.39 (s, 9H).

¹³C-NMR (CDCl₃, 75 MHz): δ 184.9, 181.1, 170.6, 154.7, 151.0, 148.8,148.3, 145.7, 145.6, 140.9, 132.7, 131.1, 130.3, 127.6, 127.0, 124.8,123.1, 119.9, 117.4, 117.1, 98.2, 80.2, 71.7, 69.3, 63.1, 60.0, 59.3,59.0, 56.1, 55.8, 55.3, 55.1, 52.8, 46.7, 41.4, 36.7, 34.8, 29.7, 28.2,25.2, 24.8, 15.8, 8.0.

MS (ES): m/z 935.3 [M+1]⁺.

Example 2 Synthesis of ET-743

Scheme IX above provides an example of the synthesis of ET-743 fromintermediate 10.

Synthesis of Intermediate 11

A suspension of 10 (56 mg, 0.06 mmol) and Pd on carbon (17 mg, 10%) inanhydrous CH₃CN (3.0 mL, 51 mL/mmol) was stirred under a hydrogenatmosphere for 2.5 h at 23° C. The reaction mixture was filtered througha 0.45 μm PTFE filter over KF (34 mg, 0.6 mmol), washed with CH₃CN (2mL), and diiodomethane (0.19 mL, 2.4 mmol) was added at 23° C. Thereaction mixture was heated for 20 h at 70° C., diluted with CH₂Cl₂, andwashed with an aqueous saturated solution of NaCl. The combined organiclayers were dried over Na₂SO₄, filtered, and concentrated under vacuum.The crude was purified by column flash chromatography over SiO₂ elutedwith CH₂Cl₂:EtOAc (from 90:10 to 80:20) to afford pure 11 (20 mg, 36%yield) which exhibited spectroscopic and spectrometric characteristicsidentical to those reported for this compound in WO 01/87895.

Compounds 12, 13, 14, 15, ET-770 and ET-743 are obtainable following theprocedures described in WO 00/69862, WO 01/87895 and WO 03/008423.

Example 3 Synthesis of Compound 17

Scheme X above provides an example of the synthesis of compound 17 fromintermediate 10.

Compounds 16 and 17 are obtainable from intermediate 15 using the sameprocedures than those previously described in WO03/014127.

The invention claimed is:
 1. A process comprising the step of reducing aquinone of formula II to form a hydroquinone, followed by alkylation ofthe resulting hydroquinone with a suitable electrophilic reagent to givea compound of formula IIa:

wherein R₁ is a protecting group for OH; R₂ is selected from substitutedor unsubstituted C₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂alkenyl, substituted or unsubstituted C₂-C₁₂ alkynyl, C(═O)R^(a),C(═O)OR^(b), C(═O)NR^(c)R^(d), and a protecting group for amino; R^(a)is selected from hydrogen, substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl, andsubstituted or unsubstituted heterocyclic group; R^(b) is independentlyselected from substituted or unsubstituted C₁-C₁₂ alkyl, substituted orunsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl, substituted or unsubstituted aryl, substituted or unsubstitutedheterocyclic group, and a protecting group for OH; R^(c) and R^(d) areindependently selected from hydrogen, substituted or unsubstitutedC₁-C₁₂ alkyl, substituted or unsubstituted C₂-C₁₂ alkenyl, substitutedor unsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heterocyclic group, and a protecting groupfor amino; Prot^(NH) is a protecting group for amino; and Prot^(sH) is aprotecting group for SH.
 2. A process according to claim 1, whichfurther comprises the step of oxidising the compound of formula IIa togive a compound of formula IIb:


3. A process according to claim 2, which further comprises the step offorming a bridged ring system to provide a compound of formula Ia:


4. A process according to claim 1 wherein Prot^(SH) is anS-9-fluorenylmethyl (Fm) group.
 5. A process according to claim 3, whichfurther comprises the step of deprotecting a compound of formula Ia togive a compound of formula Ib:


6. A process according to claim 1 wherein R₁ is a methoxyethoxymethylgroup and Prot^(NH) is a t-butoxycarbonyl group.
 7. A process accordingto claim 5, which further comprises the step of oxidising theα-aminolactone of formula Ib to the corresponding α-ketolactone offormula Id by transamination:

wherein R₃ is cyano.
 8. A process according to claim 7, which furthercomprises the step of stereospecifically forming aspirotetrahydroisoquinoline compound of formula If from theα-ketolactone of formula Id by a Pictet-Spengler reaction with thefollowing compound:

wherein X₁, and X₂ are as independently selected from hydrogen andsubstituted or unsubstituted C₁-C₁₂ alkyl.
 9. A process according toclaim 8, which further comprises the step of replacement of the cyanogroup at R₃ in the compound of formula If by a hydroxy group:


10. A process according to claim 8 wherein X₁ and X₂ are H.
 11. Aprocess according to claim 7, which further comprises the step ofstereospecifically forming a spirotetrahydro-1H-pyrido[3,4-b]indolecompound of formula Ie from the α-ketolactone of formula Id by aPictet-Spengler reaction with the following compound:

wherein Y₁ is selected from hydrogen, OR^(b), OC(═O)R^(a), OC(═O)OR^(b),OC(═O)NR^(c)R^(d), SR^(e), SOR^(a), SO₂R^(a), C(═O)R^(a), C(═O)OR^(b),C(═O)NR^(c)R^(d), NO₂, NR^(c)R^(d), N(R^(c))C(═O)R^(a), N(R^(c))—OR^(b),C(R^(a))═NOR^(b), N(R^(c))C(═O)OR^(b), N(R^(c))C(═O)NR^(c)R^(d), CN,halogen, substituted or unsubstituted C₁-C₁₂ alkyl, substituted orunsubstituted C₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂alkynyl, substituted or unsubstituted aryl, and substituted orunsubstituted heterocyclic group; Y₂, and Y₃ are independently selectedfrom hydrogen and substituted or unsubstituted C₁-C₁₂ alkyl; and R^(e)is selected from hydrogen, substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heterocyclic group, and a protecting groupfor SH.
 12. A process according to claim 11, which further comprises thestep of replacement of the cyano group at R₃ in the compound of formulaIe by a hydroxy group:


13. A process according to claim 11 wherein Y₁ is hydrogen or methoxy,and Y₂ and Y₃ are hydrogen.
 14. A process according to claim 1, whereinR₂ is methyl.
 15. A process according to claim 9 wherein the compound offormula If is ET-743:


16. A process according to claim 12, wherein the compound of formula Ieis:


17. A process according to claim 5, which further comprises the step ofconverting a compound of formula Ib into a compound of formula Ic byreaction with a compound of formula R₈LG and a compound of formula R₉LG:

wherein R₃ is cyano; R₈ and R₉ are independently selected fromsubstituted or unsubstituted C₁-C₁₂ alkyl, substituted or unsubstitutedC₂-C₁₂ alkenyl, substituted or unsubstituted C₂-C₁₂ alkynyl, substitutedor unsubstituted aryl, substituted or unsubstituted heterocyclic group,and a protecting group for amino; and LG is a leaving group.
 18. Aprocess according to claim 17, which further comprises the step ofreplacement of the cyano group at R₃ in the compound of formula Ic by ahydroxy group:


19. A process according to claim 7, which further comprises the step ofreducing the α-ketolactone of formula Id to the correspondingα-hydroxylactone followed by reaction with a compound of formula R₇LG toproduce a compound of formula Ig:

wherein R₇ is selected from substituted or unsubstituted C₁-C₁₂ alkyl,substituted or unsubstituted C₂-C₁₂ alkenyl, substituted orunsubstituted C₂-C₁₂ alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heterocyclic group, and a protecting groupfor OH.
 20. A process according to claim 19, which further comprises thestep of replacement of the cyano group at R₃ in the compound of formulaIg by a hydroxy group: